" You have control over your thoughts, and your thoughts are more powerful than you may realize. Healthy habits create a healthy mind, and a healthy mind creates healthy people. Doing something hard is the habit of building mental calluses so that when life happens, you are better prepared for it.
In prior generations, this lesson would not have been necessary. Life was harder then. Today, the miracle of modernity, relative peace, and the pursuit of creature comforts has made hardship a rarer thing. "

― Dan Crenshaw ,