Admiral William H. McRaven, a 36-year Navy SEAL veteran, gave the commencement address to the Class of 2014 at the University of Texas in Austin. He titled his talk "10 Lessons to Change the World." Here's one of his lessons to change the world:

Every day during training you were challenged with multiple physical events—long runs, long swims, obstacle courses, hours of calisthenics—something designed to test your mettle. Every event had standards—times you had to meet. If you failed to meet those standards your name was posted on a list and at the end of the day those on the list were invited to—a "circus."

A circus was two hours of additional calisthenics—designed to wear you down, to break your spirit, to force you to quit. No one wanted a circus. A circus meant that for that day you didn't measure up. A circus meant more fatigue—and more fatigue meant that the following day would be more difficult—and more circuses were likely.

But at some time during SEAL training, everyone—everyone—made the circus list. But an interesting thing happened to those who were constantly on the list. Overtime those students—who did two hours of extra calisthenics—got stronger and stronger. The pain of the circuses built inner strength, built physical resiliency.

Life is filled with circuses. You will fail. You will likely fail often. It will be painful. It will be discouraging. At times it will test you to your very core. But if you want to change the world, don't be afraid of the circuses.