Your high school PE class helped you get to know the limits of your body?! What did you do in PE class? We did things like roller skating, go bowling, etc. It was all about having fun.
The "Pacer" test.
Either play basketball, just slowly walk circles around the gym while chatting with your friends, or secretly hide under the bleachers and hang out.
We were either doing things like running a couple miles when we'd never done that before so it felt horrible or we were screwing off and passing the time.