Resting is one of the hardest things for me to do. As a trainer, I understand that rest plays a key (or maybe THE key) role in the development of fitness. Training damages your body, and fitness is created when the body repairs itself, making you stronger and fitter. If you do not allow adequate time for repair, then you are keeping your body in a constant stage of injury. And that consistently damaged state will keep you from developing the adaptations you were working for in the first place.
However, for me (and I think a lot of fit people), the psychology of resting is the worst. You feel like, if you rest, you will lose momentum. Or like you aren't doing enough. And, of course, that's a mind problem, but can become a huge barrier for your physical growth as an athlete.
Here are my strategies for getting past the fear of rest:
1. I reframed my thinking and consider any and all recovery work to be a workout. If I foam roll or stretch for 30 minutes or do light aerobic work (even walking), I write it in my log. It counts. That way I can still "do a workout" on my off day/s, but it adds to my progress rather than detract.
2. I think about rest in the sense of a single workout. If I am training and forced to rest for 10 seconds because I really can't move, it's a good thing. Forced rest is the best indication that I am working hard. In fact, if I do a workout and don't need to rest, I know I'm not working hard enough. The same applies with the larger picture: if I can get through a full week of training without needing recovery time, I'm not challenging myself enough. I should need to rest. Otherwise, I'm not working hard enough.