The body does need days to recover, think of these "off" days as recharging, eat, eat, eat, and eat some more, Playstation is great, if you don't have a girlfriend or wife, I recommend internet porn and masturbation, and LOTS of it, and even if do have a gf , I still recommend it.....but seriously, these days are just as key to your progress as time in the weight room or on the track or treadmill or wrestling mat or field of play...or whatever it is that you do, it is physical and just as important mental recovery, if you are training hard you owe it to your body, mind, and CNS to recharge, you will be a much more explosive athlete than if you run yourself down.