It's easy to have goals and desires when you're sitting down relaxed - but you have to want it even when you are at your breaking point. If not what's going to ultimately stop you from quitting at some point?
Mindset is the way you approach a situation and handle the outcome. If you can't be optimistic at least be realistic: The glass may only be half full but at least there's water in it.
That old saying of mind over matter rings true.
Athlete mindset is quite similar to a Warrior's Mentality - it's win or suffer the ultimate shame and defeat. Be prepared to go to war in your respective craft - A Lawyer wouldn't prepare a case with evidence they thought they would lose with, they bring their A-game and fighting spirit. We remind you that even though you may have uncertain thoughts, keep your Warrior Mindset. The belief that you can accomplish a goal or any task is power enough to potentially do it.
The best trait of a strong mindset is that you flow with the energies of life - don't get too emotionally attached to things that hurt and don't waste time on the small details in life when the big things can quite literally walk right past you. Focus on what matters at all points and remember to have fun - you won't get out of life alive.