The next time, you challenge yourself to do either more steps or faster times. Both kinds of workout (
distance and speed) are important. Some long-
distance runners will do long, slow distance in one workout, and speed work in the next, and trade them off like that.
If there is a coach at your school, you can probably get some basic exercises from him or her. I'd just drop by after school if the coach has a minute, and ask for, say, ten exercises.