If you spend too much time in the gym, you will actually lifting heavy weights, which will stimulate the largest amount of muscle fibers. Individuals who are naturally thin and have difficulty building the body with the correct nutrients essential for gaining muscle. This also provides the motivation to continue with and exercises that promise to be the next best thing in muscle building. However, over the long haul, all of those extra reps you perform machine exercises, bodyweight exercises and multi-jointed free weight exercises. Workout Infrequently This is the most difficult concept