Why do we procrastinate?
Sometimes I think it's self fulfilling. We hear from others how they put off work, or exercise and we subtly adopt those attitudes. Then we talk the same way, and that re-enforces those attitudes in others.
That may be an oversimplification.
I lifted weights today-- for the first time in a very long time. It felt good. And it's not like I put off anything fun to find the time to work out. I know there is lots of time in my life for me to exercise more. I end up watching TV instead. Bad TV. I don't enjoy most of the TV that I watch.
See how little sense my exercise procrastination makes?