I know, most of you who read this think an interval is the time between dinner and your bedtime snack, but I'm thinking about upping my fitness by doing some Intervals.
An Interval (I use the capital with respect) is doing something so hard, like an all-out sprint on the bicycle, that you not just think, you know you're going to die, and then not doing the so-hard-you-could-die thing for an Interval, called Recovery, oh yeah! and then repeating the, yes-this-time-I-know-it's-the-end-for-sure, I-will-now-die thing again. Oh, and then you do it a few more times.
That's doing intervals.
There are losing-fat intervals, building-muscles intervals, and speed-training intervals, etc., etc., etc.
I plan to sprint between red lights on 7th Street, on my way to school. If I haven't dropped dead by Market (it's a slight grade, to boot), I will slowly recover and then sprint that last climb up Golden Gate to U.S.F.
You probably won't want to sit next to me in class.