Mental toughness is a phrase people in the sports world throw around all the time, but what does it really mean? Recently I was reading an article in The Players’ Tribune about professional football player Brandon Marshall, and while the article wasn’t about mental toughness, Marshall did mention what it meant to him: “...Masking pain. Hiding it. Keeping it inside. That had been embedded in me since I was a kid. Never show weakness. Suck it up. Play through it. Live through i