Your body is an efficient system, and adapts only when it must. It your body and mind do not need to grow, they will not grow. To experience growth, you must demand growth. To improve yourself you commit to pushing yourself to the very limit of your capabilities, not the limit that is set in your mind. The limit your mind has for yourself and your true potential limit are infinitely different. If your body cannot handle cold weather, take a cold shower. When you want to get out, and your body is screaming for survival, stay. Pushing yourself to the absolute limits is the only way to provoke deep, and vast growth of self.