Nothing like a run...
I was on the subway, in my sweats, and felt a tickle in my throat, I've been worried that I"m getting a cold, so I told myself "you've made it this far, just go to the Y, and give yourself an easy workout - something is better than nothing". So, I got on a treadmill, set it for 40 minutes, 1.5 incline, and started slow, that was boring, so I pushed up to ten miniute mile (nothing impressive, but enough that my heart knows it is happening). I kept moving, at that rate, although the tilt came down after a while, and finished with 4.25 miles completed, a vim to do anything and the high of a good run.
It was great! I added some core work, and still made it into work before my boss.