I am a seasoned instructor of taekwon-do, and love working with all the kids; oftentimes I talk about the important things in life with them: How to handle life and all the odd balls it'll throw at you. I am currently trying to find some insight into how this is addressed in the philosophy of martial arts generally, and taekwon-do specifically. In particular, how are mental illnesses¹ considered in the practicing of martial arts in the philosophical teachings of the old masters. What, if anything, did General Choi and his peers (then and current) have to say on this subject?

¹ Examples include, but are not necessarily limited to:

* clinical depression, or anxiety
* PTSD (e.g. from years of being bullied—yes, this diagnosis is also given to non-combatants)
* eating disorder

To clarify, this question has to be concerned with ITF taekwon-do, though influences from Shotokan karate would also be of interest, considering the background of early taekwon-do practioners in general, and Choi in particular.