What is an action? Well, I can only really tell you this by telling you what is not an action. So, given there are many chaotic interpretations of what is not an action, lets consider this; in a metaphysical cycle of universe after universe, all inaction is the inaccurate mistake where evolutionary possibilities have been missed and therefor have never really happened.
But of course, I must also explain the obvious, 'doing nothing' is still an action. In fact if you can successfully achieve the action of nothing (a state of stillness not forgetfulness) then you have achieved the action of enlightenment and you ARE everything. If you fail, you'll merely achieve a fly up your nose, end of story.
But this philosophy of mischance, of faults, failures and ignorance's as 'inactions' and therefor non-events in space-time evolution, of course, doesn't mean I'm advocating that you smash your car into parliament and 'that's o.k.' because it didn't really happen.
No, interestingly the word 'sin' is actually derived from the word 'miss.' Unfortunately, the static nature of a resonance memory field of what NOT to do next time you come back to that place-time doesn't exist. However, there are resonance fields around a potential true action. Indeed, a field the previous universe remembered for you, a field where you can think "ahh this moment is close to an action of truth, an action of compassion and existential accuracy... lets see if I can..."