Believe it or not, your muscles do not get stronger during your workout; it’s after the workout that they grow and develop. Intense strength training places huge demands on your muscles. To adapt to those demands, your muscles need adequate recovery time to rebuild and get stronger. As important as it is to stay the course and not get lazy, it’s just as important to know when to cut yourself a break so you don’t burn out, and your body has a chance to process all of the work you’re doing.
Do not train a muscle group more than twice a week, and make sure it rests between training sessions. I want you to have at least two days in between training the same muscle groups. When you work a muscle, the muscle fibers tear. Given the proper rest and discovery, your muscle fibers will repair themselves and grow leaner and stronger. But if you train the muscle too soon and impede its recovery, you can damage the muscle and break it down.
Additionally, you should never exercise intensely for more than two hours at a time. When you hear some buff celebrity talking about how he trained six hours straight a day to get ready for his latest action movie, he’s talking a load of embellished bull that makes the ordinary person feel totally inferior. We have lives, we can’t possibly do that! However, spending that much time working out is not only impossible, it would be counterproductive, as it would throw the body into a state of overtraining and make it more prone to metabolize its own lean muscle tissue for energy.