What is mental toughness? Mental toughness is that little voice at the back of your head that tells you to keep pushing on, even when the odds aren't in your favor. People who master mental toughness are resilient, strong, and in control of their emotions. They do not fear to fail and view failure as a learning experience rather than a predicament. The mentally tough athlete, entrepreneur, or professional doesn't give up. He or she has learned to harness self-confidence, self-assurance, mental strength, and focus to ride the success wave. Mental toughness is the one key quality that the most successful people in business, politics, music, and a lot of other fields leverage today.