Going to train is important, what you do afterwards is equally important, these three steps you can not forget, when you are in any activity, be it lifting weights, swimming, running, etc., your muscles are consuming the glycogen reserves of your body, increases your temperature and increases your heart rate, you lose water through sweating and metabolic processes, muscle fibers are broken because of the effort, your body is a machine designed to make efforts of all kinds, but most importantly is that after you give him what he has lost and it is not more than:
Rehydration: as your body lost water at an accelerated rate during exercise, be sure to drink water during and especially after exercise, do not wait until you are thirsty.
Regeneration: the muscle does not grow in the gym, but at night, after the effort you need proteins, which are the building material, and sleep enough hours.
Fill: after training is the time when you should eat carbohydrates, which will replenish your glycogen reserves better if they are complex.