Do I Gotta?

I was thinking about the different types of motivation.  I am sure there is a whole field of study that looks into such things, but I was just considering what makes me tick.
Sometimes the motivation is just a necessity.  It might be a thing like “mow the lawn.”  Guarente’d there comes a time where it just has to be done.  Having said that I am not sure the guy down the road got the memo.  His yard was a jungle for years.  Imagine my surprise when I learned he worked for Bunnings.  I do not think a lack of access to tools was the problem.  To me sometimes choice is built on the lack of choice – but not that time.
At other times the motivation is easy peasy.  It is something I enjoy big time and will do pretty well every time where appropriate.   Getting together with friends is pretty well a no brainer for me.
The motivation that I am really thinking about at present is doing things out of a sense of self-imposed necessity.  Where no one else demands the doing of something except myself. 
It is a weird one and one which I am having trouble explaining to myself.  I guess it is less about what I do, but the how I do what I do. In many aspects of life, I can be unnecessarily hard on myself.  This is not talking about self-discipline or doing something I should even if I do not feel like it.  For me that is just like a “get over it” thing.
No, what I am taking about is determining if sometimes my motivation is born of a “law” thing rather than a “liberty” thing.  That is, doing something in the mistaken belief that doing it is a must and not doing it will be a failure on my part.
I have come to the conclusion that that is a motivation to be avoided.  To me there will always be “blah” times which would see me rather not do something I really should or normally want to do.  But I reckon they are very different to motivations I seemingly force on myself, which, when examined, can be ignored without peril to anyone.
There are times I have no answer to “why” and as a consequence do not do what I have always unthinkingly done.
The amazing thing is, nothing happens – except maybe on the inside of me.  I feel relief. What I do I continue to do. not just of necessity but willingly.
I am going to stop now before my brain explodes.