For example, you could set a cron job to run this script once per hour to help you keep track of how many PHP sessions are being used around the clock.

Or, when you have to take the kids to soccer or swimming, take their workout time to run the soccer field or around the school track instead of sitting on the sidelines.

I played tennis in high school, but when my coach wanted me to run a couple of laps around the track, I almost passed out.