I have to agree with the other comment about intense cardio. I got into long-distance running last year and it was a big mental shift for me to go from fast to

I have to agree with the other comment about intense cardio. I got into long-distance running last year and it was a big mental shift for me to go from fast to slow running. Before that, I had always approached exercise as if harder is better. I was surprised to learn that even elite runners are doing 80% of their training at a pace that's really slow relative to their race pace. Of course training plans will vary depending on the target distance, but I think this still applies if you are training for shorter distances. Training at max effort is a recipe for getting injured, and it prevents you from putting in the volume necessary to develop good cardio.