David Goggins goes into this in detail https://m.youtube.com/watch?v=5tSTk1083VY
Essentially what ever you are afraid of you should probably doing it.
The Science of Well-Being
In this course you will engage in a series of challenges designed to increase your own happiness and build more productive habits. As preparation for these tasks, Professor Laurie Santos reveals misconceptions about happiness, annoying features of the mind that lead us to think the way we do, and the research that can help us change. You will ultimately be prepared to successfully incorporate a specific wellness activity into your life.