It's good to remind yourself, occasionally, what your body can do.
Lift things that may be a bit, oh I don't know, heavy beyond your strength.
Run a little farther than you ran before. Don't die. See how it feels to have legs of Jell-O, burning lungs, sweaty shorts, and accomplishment.
Walk a long way. Just walk. Know that the car could have taken you there in about 1/10th of the time. Know that your healthier mentally and physically for doing so.
Ride your bike a bit further, with no real destination. Just let the sun beat on your back a little. Feel the breeze. Pedal a bit faster.
I did a few of these today. I took a walk from 63rd street back to my home nearly 40 blocks away. It felt...liberating I think is the word. The weather was beautiful, and it was fun to lip sync to the iPod music and slash on the edge of the water. Earlier, I took my bike down the boardwalk (I figure 6 miles of bike riding MUST be good for my soul and body). It was a lovely morning, and the breeze smelled perfectly of salt water and the early-going-beach-visitors' sunscreen. I feel better. Calmer. Happier.
It's nice to know I can. And that I did. Possibility and actuality meet.