I'm extremely uncomfortable with rest days and right now I'm up close and personal with that feeling as I type this on a rest day. I'm not even training for anything in particular right now and still a complete day off has me bouncing between depressed and climbing the walls. But I know I need it so I'll do it anyway.
What I've learned about training is that the days in between are vital to improvement in your sport. Especially as I get older I need to give my body time to adapt, heal and build muscle. Failing to do so results in weakness, soreness, lacklustre training efforts or even worse, injury. So at a minimum I like to take one full day a week with very light or no training at all, not even cross training. If I do anything at all it will be a walk, gentle short swim or easy yoga class.
Ideally I'd simply ensure I slept well, ate nutritiously and avoided undo stress on rest days. Often the anxiety of sitting around has me fidgety, feeling kind of sad and seeking junk food. I think good rest days might be best scheduled to heavy (real life job) work days just to keep my mind and hands busy.
One way or another I sincerely believe despite my struggles that taking a day off from training on a regular basis is only going to help you in the long run. Today I have sore fingers (boxing) and my left calf is knotted up pretty good from a double run yesterday. If I show some discipline I'll be at the track tomorrow ready to train. If not I'll just be limping lethargically in circles.