I found that when I was dopamine deficient, I couldn't initiate exercise myself. I could tag along if someone else initiated it though, and feel better during and after. A woman from my church invited me to go walk with her on Tuesday mornings, and I could do that. My husband and I joined a twice weekly yoga class, and I could go to that.
It seemed silly to me that I couldn't initiate these sorts of things myself. In the past I treated this as a moral failing, and beat myself up about it. That made me feel awful, but I still mostly wouldn't be able to do it. This most recent time I was more accepting about it. I still tried to convince myself to go exercise, but was more gentle about it. Sometimes I would succeed in going and exercising by myself, but mostly I wouldn't. Instead of treating it as a moral failing, I treated it as a science experiment. What was different about the times when I was able to go and exercise?
Once I got the dopamine increased enough I could mostly initiate exercise by myself no problem. It wasn't that I was trying harder, or being more morally upright. It just felt like a road block that had been there was just gone.
When I studied more about dopamine, and what affects it, I realized that dopamine levels seemed to correspond to how easy or hard it was to initiate that sort of activity. When dopamine levels were mostly low, I would only be able to do it as a follower or after some sort of experience that sufficiently increased dopamine. Now that dopamine levels are mostly ok (got the bupropion working right), I can initiate exercise myself most of the time, except after experiences that sufficiently decrease dopamine.
All this made me realize that the concept we call "motivation" really has more facets than I'd realized before. What you think about how much you "should" do something, how much you want to do it, and what you think about where it ranks in your priority and value schemes are one set of factors. How you feel when your think about doing something -- how your biochemistry reacts to the idea -- is another. They're controlled by different parts of your brain (cortex vs. limbic system), and are not always in sync.
I suspect that the latter part is the one that's more tied into physiological state -- how much dopamine, energy, etc. you've got to start with and how those change in reaction to your proposed activity, like exercise. It can agree and reward you with an added burst of dopamine, which makes it real easy and appealing to go off and initiate the activity. It can also disagree and make you feel uneasy about it (not sure if this is it decreasing dopamine, increasing stress chemicals, or both), and make it real hard.
It seems to me that in some cases the meaning of "motivation" is pretty clear:
- Motivated = cortex decides to do it, limbic system agrees, you do it
- Unmotivated = cortex decides not to do it
I certainly find myself in that state much less often now. For a few months, before using the bupropion to increase dopamine tone, I was in that state almost all the time. I exercise much more often now than I did then. I don't actually decide to exercise any more often -- likely I decide to do it less frequently. The difference is that now it's much easier to follow through on that decision. Does that reflect a difference in "motivation" or not?