Another tip: pace yourself during the workout. I used to start out going balls to the wall, and by the time the third interval came around, I'd be spent. Including the warm-up. I was trying to keep up with the people in the video until I realized they were all about 20 years younger.
So during the interval days, I typically start out slow/moderate for set 1, go a bit faster in set 2 but still able to breathe (say, 70% effort), then go all out in the final set. This is easier to measure with a HR monitor, you can track how you're doing in the middle of each set--I'll typically hit something like 125, 140, 160.