diff --git a/my/core/__main__.py b/my/core/__main__.py
index e399c11..25eab7f 100644
--- a/my/core/__main__.py
+++ b/my/core/__main__.py
@@ -140,19 +140,21 @@ def modules_check(args):
     module: Optional[str] = args.module
     vw = '' if verbose else '; pass --verbose to print more information'
 
-    mods: Iterable[str]
+    from .util import get_stats, HPIModule, modules
+    from .core_config import config
+
+    mods: Iterable[HPIModule]
     if module is None:
-        from .util import modules
         mods = modules()
     else:
-        mods = [module]
+        mods = [HPIModule(name=module, skip_reason=None)]
 
-    from .core_config import config
     # todo add a --all argument to disregard is_active check?
-    for m in mods:
-        active = config.is_module_active(m)
-        if not active:
-            eprint(f'🔲 {color.YELLOW}SKIP{color.RESET}: {m:<30} module disabled in config')
+    for mr in mods:
+        skip = mr.skip_reason
+        m    = mr.name
+        if skip is not None:
+            eprint(f'🔲 {color.YELLOW}SKIP{color.RESET}: {m:<30} {skip}')
             continue
 
         try:
@@ -165,7 +167,7 @@ def modules_check(args):
             continue
 
         info(f'{color.GREEN}OK{color.RESET}  : {m:<30}')
-        stats = getattr(mod, 'stats', None)
+        stats = get_stats(m)
         if stats is None:
             continue
         from . import common
@@ -188,8 +190,11 @@ def list_modules(args) -> None:
 
     # todo add an active_modules() method? would be useful for doctor?
     from .util import modules
-    for m in modules():
-        active = config.is_module_active(m)
+    for mr in modules():
+        m    = mr.name
+        skip = mr.skip_reason
+
+        active = skip is None
         # todo maybe reorder? (e.g. enabled first/last)? or/and color?
         # todo maybe use [off] / [ON] so it's easier to distinguish visually?
         print(f'- {m:50}' + ('' if active else f' {color.YELLOW}[disabled]{color.RESET}'))
diff --git a/my/core/core_config.py b/my/core/core_config.py
index c4f8ec0..b180aee 100644
--- a/my/core/core_config.py
+++ b/my/core/core_config.py
@@ -37,33 +37,33 @@ class Config(user_config):
     disabled_modules: Optional[Sequence[str]] = None
 
 
-    def is_module_active(self, module: str) -> bool:
+    def _is_module_active(self, module: str) -> Optional[bool]:
+        # None means the config doesn't specify anything
         # todo might be nice to return the 'reason' too? e.g. which option has matched
-        should_enable  = None
-        should_disable = None
-        def matches(specs: Sequence[str]) -> bool:
+        def matches(specs: Sequence[str]) -> Optional[str]:
             for spec in specs:
                 # not sure because . (packages separate) matches anything, but I guess unlikely to clash
                 if re.match(spec, module):
-                    return True
-            return False
+                    return spec
+            return None
 
         enabled  = self.enabled_modules
         disabled = self.disabled_modules
-        if enabled is None:
-            if disabled is None:
-                # by default, enable everything? not sure
+        on  = matches(self.enabled_modules  or [])
+        off = matches(self.disabled_modules or [])
+
+        if on is None:
+            if off is None:
+                # user is indifferent
+                return None
+            else:
+                return False
+        else: # not None
+            if off is None:
                 return True
-            else:
-                # only disable the specified modules
-                return not matches(disabled)
-        else:
-            if disabled is None:
-                # only enable the specified modules
-                return matches(enabled)
-            else:
-                # ok, this means the config is inconsistent. better fallback onto the 'enable everything', then the user will notice?
-                warnings.medium("Both 'enabled_modules' and 'disabled_modules' are set in the config. Please only use one of them.")
+            else: # not None
+                # fallback onto the 'enable everything', then the user will notice
+                warnings.medium(f"[module]: conflicting regexes '{on}' and '{off}' are set in the config. Please only use one of them.")
                 return True
 
 
@@ -72,42 +72,39 @@ config = make_config(Config)
 
 
 ### tests start
+from contextlib import contextmanager as ctx
+@ctx
+def _reset_config():
+    # todo maybe have this decorator for the whole of my.config?
+    from .cfg import override_config
+    with override_config(config) as cc:
+        cc.enabled_modules  = None
+        cc.disabled_modules = None
+        yield cc
+
 
 def test_active_modules() -> None:
-    # todo maybe have this decorator for the whole of my.config?
-    from contextlib import contextmanager as ctx
-    @ctx
-    def reset():
-        from .cfg import override_config
-        with override_config(config) as cc:
-            cc.enabled_modules  = None
-            cc.disabled_modules = None
-            yield cc
+    reset = _reset_config
 
     with reset() as cc:
-        assert cc.is_module_active('my.whatever')
-        assert cc.is_module_active('my.core'    )
-        assert cc.is_module_active('my.body.exercise')
+        assert cc._is_module_active('my.whatever'     ) is None
+        assert cc._is_module_active('my.core'         ) is None
+        assert cc._is_module_active('my.body.exercise') is None
 
     with reset() as cc:
+        cc.enabled_modules  = ['my.whatever']
         cc.disabled_modules = ['my.body.*']
-        assert cc.is_module_active('my.whatever')
-        assert cc.is_module_active('my.core'    )
-        assert not cc.is_module_active('my.body.exercise')
-
-    with reset() as cc:
-        cc.enabled_modules = ['my.whatever']
-        assert cc.is_module_active('my.whatever')
-        assert not cc.is_module_active('my.core'    )
-        assert not cc.is_module_active('my.body.exercise')
+        assert     cc._is_module_active('my.whatever'     ) is True
+        assert     cc._is_module_active('my.core'         ) is None
+        assert not cc._is_module_active('my.body.exercise') is True
 
     with reset() as cc:
         # if both are set, enable all
         cc.disabled_modules = ['my.body.*']
-        cc.enabled_modules = ['my.whatever']
-        assert cc.is_module_active('my.whatever')
-        assert cc.is_module_active('my.core'    )
-        assert cc.is_module_active('my.body.exercise')
+        cc.enabled_modules =  ['my.body.exercise']
+        assert cc._is_module_active('my.whatever'     ) is None
+        assert cc._is_module_active('my.core'         ) is None
+        assert cc._is_module_active('my.body.exercise') is True
         # todo suppress warnings during the tests?
 
 ### tests end
diff --git a/my/core/util.py b/my/core/util.py
index e1a9e8b..cb2f599 100644
--- a/my/core/util.py
+++ b/my/core/util.py
@@ -1,20 +1,87 @@
 from pathlib import Path
 from itertools import chain
+from importlib import import_module
 import os
-import re
 import pkgutil
-from typing import List, Iterable
+import re
+import sys
+from typing import List, Iterable, NamedTuple, Optional
 
-# TODO reuse in readme/blog post
+
+class HPIModule(NamedTuple):
+    name: str
+    skip_reason: Optional[str]
+
+
+def modules() -> Iterable[HPIModule]:
+    import my
+    for m in _iter_all_importables(my):
+        yield m
+
+
+def ignored(m: str) -> bool:
+    excluded = [
+        'core.*',
+        'config.*',
+        ## todo move these to core
+        'kython.*',
+        'mycfg_stub',
+        ##
+
+        ## these are just deprecated
+        'common',
+        'error',
+        'cfg',
+        ##
+
+        ## TODO vvv these should be moved away from here
+        'jawbone.plots',
+        'emfit.plot',
+        # 'google.takeout.paths',
+        'bluemaestro.check',
+        'location.__main__',
+        'photos.utils',
+        'books',
+        'coding',
+        'media',
+        'reading',
+        '_rss',
+        'twitter.common',
+        'rss.common',
+        'lastfm.fill_influxdb',
+    ]
+    exs = '|'.join(excluded)
+    return re.match(f'^my.({exs})$', m) is not None
+
+
+def get_stats(module: str):
+    # todo detect via ast?
+    try:
+        mod = import_module(module)
+    except Exception as e:
+        return None
+
+    return getattr(mod, 'stats', None)
+
+
+__NOT_A_MODULE__ = 'Import this to mark a python file as a helper, not an actual module'
+
+
+# todo reuse in readme/blog post
 # borrowed from https://github.com/sanitizers/octomachinery/blob/24288774d6dcf977c5033ae11311dbff89394c89/tests/circular_imports_test.py#L22-L55
-def _iter_all_importables(pkg):
+def _iter_all_importables(pkg) -> Iterable[HPIModule]:
+    # todo crap. why does it include some stuff three times??
     yield from chain.from_iterable(
         _discover_path_importables(Path(p), pkg.__name__)
-        for p in pkg.__path__
+        # todo might need to handle __path__ for individual modules too?
+        # not sure why __path__ was duplicated, but it did happen..
+        for p in set(pkg.__path__)
     )
 
 
-def _discover_path_importables(pkg_pth, pkg_name):
+def _discover_path_importables(pkg_pth, pkg_name) -> Iterable[HPIModule]:
+    from .core_config import config
+
     """Yield all importables under a given path and package."""
     for dir_path, dirs, file_names in os.walk(pkg_pth):
         file_names.sort()
@@ -32,53 +99,105 @@ def _discover_path_importables(pkg_pth, pkg_name):
         rel_pt = pkg_dir_path.relative_to(pkg_pth)
         pkg_pref = '.'.join((pkg_name, ) + rel_pt.parts)
 
-
-        # TODO might need to make it defensive and yield Exception (otherwise hpi doctor might fail for no good reason)
-        yield from (
-            pkg_path
-            for _, pkg_path, _ in pkgutil.walk_packages(
-                (str(pkg_dir_path), ), prefix=f'{pkg_pref}.',
-            )
+        yield from _walk_packages(
+            (str(pkg_dir_path), ), prefix=f'{pkg_pref}.',
         )
+        # TODO might need to make it defensive and yield Exception (otherwise hpi doctor might fail for no good reason)
+        # use onerror=?
+
+# ignored explicitly     -> not HPI
+# if enabled  in config  -> HPI
+# if disabled in config  -> HPI
+# otherwise, check for stats
+# recursion is relied upon using .*
+# TODO when do we need to recurse?
 
 
-# TODO marking hpi modules or unmarking non-modules? not sure what's worse
-def ignored(m: str):
-    excluded = [
-        'kython.*',
-        'mycfg_stub',
-        'common',
-        'error',
-        'cfg',
-        'core.*',
-        'config.*',
-        'jawbone.plots',
-        'emfit.plot',
+def _walk_packages(path=None, prefix='', onerror=None) -> Iterable[HPIModule]:
+    '''
+    Modified version of https://github.com/python/cpython/blob/d50a0700265536a20bcce3fb108c954746d97625/Lib/pkgutil.py#L53,
+    to alvoid importing modules that are skipped
+    '''
+    from .core_config import config
 
-        # todo think about these...
-        # 'google.takeout.paths',
-        'bluemaestro.check',
-        'location.__main__',
-        'photos.utils',
-        'books',
-        'coding',
-        'media',
-        'reading',
-        '_rss',
-        'twitter.common',
-        'rss.common',
-        'lastfm.fill_influxdb',
-    ]
-    exs = '|'.join(excluded)
-    return re.match(f'^my.({exs})$', m)
+    def seen(p, m={}):
+        if p in m:
+            return True
+        m[p] = True
 
+    for info in pkgutil.iter_modules(path, prefix):
+        mname = info.name
 
-def modules() -> Iterable[str]:
-    import my as pkg # todo not sure?
-    for x in _iter_all_importables(pkg):
-        if not ignored(x):
-            yield x
+        if ignored(mname):
+            # not sure if need to yield?
+            continue
 
+        active = config._is_module_active(mname)
+        skip_reason = None
+        if active is False:
+            skip_reason = 'suppressed in the user config'
+        elif active is None:
+            # unspecified by the user, rely on other means
+            # stats detection is the last resort (because it actually tries to import)
+            stats = get_stats(mname)
+            if stats is None:
+                skip_reason = "has no 'stats()' function"
+        else: # active is True
+            # nothing to do, enabled explicitly
+            pass
 
-def get_modules() -> List[str]:
+        yield HPIModule(
+            name=mname,
+            skip_reason=skip_reason,
+        )
+        if not info.ispkg:
+            continue
+
+        recurse = config._is_module_active(mname + '.')
+        if not recurse:
+            continue
+
+        try:
+            __import__(mname)
+        except ImportError:
+            if onerror is not None:
+                onerror(mname)
+        except Exception:
+            if onerror is not None:
+                onerror(mname)
+            else:
+                raise
+        else:
+            path = getattr(sys.modules[mname], '__path__', None) or []
+            # don't traverse path items we've seen before
+            path = [p for p in path if not seen(p)]
+            yield from _walk_packages(path, mname+'.', onerror)
+
+# deprecate?
+def get_modules() -> List[HPIModule]:
     return list(modules())
+
+
+
+### tests start
+
+## FIXME: add test when there is an import error -- should be defensive and yield exception
+
+def test_module_detection() -> None:
+    from .core_config import _reset_config as reset
+    with reset() as cc:
+        cc.disabled_modules = ['my.location.*', 'my.body.*', 'my.workouts.*', 'my.private.*']
+        mods = {m.name: m for m in modules()}
+        assert mods['my.demo']  .skip_reason == "has no 'stats()' function"
+
+    with reset() as cc:
+        cc.disabled_modules = ['my.location.*', 'my.body.*', 'my.workouts.*', 'my.private.*', 'my.lastfm']
+        cc.enabled_modules  = ['my.demo']
+        mods = {m.name: m for m in modules()}
+
+        assert mods['my.demo']  .skip_reason is None # not skipped
+        assert mods['my.lastfm'].skip_reason == "suppressed in the user config"
+
+
+
+### tests end
diff --git a/tests/core.py b/tests/core.py
index 0997527..0ffd225 100644
--- a/tests/core.py
+++ b/tests/core.py
@@ -11,4 +11,5 @@ we can run against the tests in my.core directly.
 '''
 
 from my.core.core_config import *
-from my.core.error import *
+from my.core.error       import *
+from my.core.util        import *