Mental toughness is built by doing something that is hard over and over again, especially when you don’t feel like doing it. Our society has conditioned us to believe that there should be no discomfort, to stop when we are uncomfortable. But the discomfort we feel when we’re doing a challenging workout is an important part of the strengthening process. Push though your down days when you’re not feeling your best. Dogged determination requires keeping your feet moving forward through inconveniences, discomfort, and insecurities to reach your goals.
—Runner’s World, Jan. 2014