You should do it against the clock. Say you are going to do 30 laps in 15 minutes. Then you try to do it each day a little faster. That is putting demands on the body, and that is how you build up. You keep up your energy instead of going downhill.
Jack LaLanneI never think of my age, never. I could be 20 or 100. I never think about it, I'm just me.
Jack LaLanne