What is the key to being motivated into action (or inaction)? It seems like it should be so simple; you either want to do something or you don't, then you either do it or don't. Simple, eh? Then what's up with all the unfinished (and un-started) projects?
Primacy of the body: all action is an expression through our body, usually in response to our body. Our attachment to the senses seems to be the starting point for most action or inaction. In all living creatures and plants, desire and aversion are associated with sensory experience. The basic motivation for all organisms is pain avoidance. All organisms try to move away from painful experiences and toward comfortable and pleasurable experiences. Even non-sentient (or low-sentience) organism move toward food and away from injury (pain). This is easily observed in microbes and plants, as well as higher creatures. This is a basic operation for survival and the reason for pain.
But it gets a little more complicated when we add a brain. The part of the conditioned mind that arises from the central nervous system can imagine pleasure and pain, and so act in anticipation. But often the conditioned mind mis-associates behaviors as painful or pleasant. We attach to imagined ideas about sensual fulfillment or potential injury (physical or emotional) and act as if the experience were real, rather than imagined. Still that doesn't explain how we can imagine a particular action for a desired outcome and still not act, or worse, do something we imagined we didn't want to do.
The simplest explanation is our habit-molds or 'samskaras'. Our karmic conditioning creates these samskaras and then we usually react to external events and stimuli from habituation rather than genuine volition. Our conditioned mind being the wonderfully complex thing it is, we imagine that our reaction was a choice. One of the benefits of a regular meditation practice (according to the Dalai Lama) is that we begin to see 'the gap'; that brief moment between an event and our habituated reaction. The more clearly we experience 'the gap' the more able we are to choose our response (free will volition) instead of unconscious reaction.
But what about the things we imagine we want to do but then don't? Even if my inaction is an expression of some samskara, shouldn't my awareness of that empower me to act?
One of my students is a brain researcher. She has been studying people with Parkinson's disease. A common problem for Parkinson's patients is an inability to make themselves perform certain tasks. They can usually do queue driven tasks, but then may be unable to perform a self initiated task. The example she shared with me was about a client going to catch a bus. Once started, he was able to walk to the bus-stop (queued action, one foot after the other), but once the bus arrived he was unable to get off the bench and onto the bus (self-initiated, need to get started). Wouldn't that be horrible - knowing that you want to move, your body is capable of the movement, but you just sit there.
Is that really that much different from having a list of things I think I want to do, and still not doing them? I hope you weren't expecting an answer here. Now I need to look at my to-do list and see what I will do.