The linked article is one that I’ve seen reposted on FB quite a few times lately. I agree with the article to an extent, but its important to recognize that mental toughness is largely controlled by genetics and psychology (nurture). It is somewhat trainable. I’ve experienced it myself, but I was ready and willing to suffer before I was able to suffer more. The ability to follow the path of suffering deeper into the unknown is not something I feel like is a conscious decision. I even feel like suffering and pain management is somewhat periodized naturally in a well developed training plan. So looking at the qualities that make someone a better athlete, you have mental toughness, physiology, and data processing. The last one is something many people overlook. You can train yourself to suffer through the next pain notch and you can do intervals to increase your threshold, but what do you do about that last item? Coaching keeps you from having to re-invent the wheel and keeps you focussed on consistent development. Specific and intentional practice will develop muscle memory and movements to make you more efficient. Higher fitness gives you higher awareness of your surroundings, providing clear data for your brain to process and make decisions. Its all about efficiency folks.