Having mental toughness gives you endurance and a degree of immunity to exhaustion because it enables you to ignore the first onset of fatigue and find your second wind, both in physical and mental exertion.
This makes a prolonged effort at something easier.
It means having a constitutional boldness when attempting difficult assignments or tasks where success isn't a sure thing.
The more you train yourself to be mentally tough, the more daring and determination you will have.
It will drive you to climb over obstacles that would daunt conservative judgement or ordinary courage and help you set your teeth and bring home success even from apparent failure.
Mental toughness is frequently found in people who have vision and excellent judgement.
What better advantage in life can you have than passion and perseverance to get you where you want to go?