Mental toughness is a central concept of
Stoic philosophy, which originated in ancient Greece. Stoics teach that you should differentiate between the things that you
can control and the things that you
can't.
Even when you can't control or change a specific situation or circumstance, you can still control your reaction to it. Ideally, stay mentally strong and accept it, and then focus on the things you
can control. This is one of the best exercises for mental toughness.