When you want to have strong muscles, you should practice until you die when you exercise, and you won't be tired. I used to do this. I am a dumbbell, and I exercise all over four days a day. But sometimes I'm just a little lazy, so I don't do much! It is often said that perseverance is the key to fitness. This is a state of mind. Just put your mind right, and malnutrition is also the reason why you can't afford it.