Wear out. Don't rust out.
Heh I have a feeling that'll be my motto in my late fifties. While lifting at the Y today I chatted with some 70+ year old guy who was doing some hefty leg squats. As he walked away he said the above quote. I wish the weight room was a little better at the Y... actually I wish I had my own weight room in my house. Summer hours are starting soon, I'd better get used to lifting in the mornings again.