That is not true. Even humans work out, causing pain, but do so anyway because it makes the body stronger. Muay Thai practitioners roll their shins and smack t

That is not true. Even humans work out, causing pain, but do so anyway because it makes the body stronger. Muay Thai practitioners roll their shins and smack them against trees, causing pain. Anxiety often induced animals to cause pain to themselves in the form of self-harm. And so on and so forth.