There are a lot of people who think their own personal athletic accomplishments are their legacy. They are under the impression that if they can run the fastest marathon or be the best Ironman that they are leaving a legacy. A true legacy is not what you do, however, but what you inspire others to do. How many people have you led to the next level? How many kids have you taught and coached to be better people as well as athletes? How many staff members have you encouraged and assisted to better themselves?
Being an athlete and accomplishing personal goals is fantastic and indeed has merit unto itself, but the real "legacy" you leave is about who you were as a person. Nobody remembers for long if you were fast or slow; what they remember is who you were while you were being fast or slow. They remember what impact you had on them, not what you accomplished for yourself. This, of course, has its exceptions. There are a few transcendent athletes who are the best of their generation or perhaps of all time and their accomplishments leave a legacy by themselves. For 99% of athletes, though, the legacy you leave has nothing to do with your athletic achievements.
Challenging yourself everyday and trying to accomplish great things in your life is a wonderful motivator, but it is not leaving a legacy. It's when you are challenging others and leading them to accomplish good things that you are leaving a lasting impression. When you are developing your next goal or challenge, why not take somebody else along for the ride? Why not leave a legacy by working with charities and kids? Take the time to help someone else accomplish something amazing for themselves and you will leave a legacy. Work with others to develop their motivation and complete their goals and they will remember you forever. When you accomplish something amazing yourself, you have a legitimate reason for pride. The impact is for you, however, not for others. When you work with others, the impact is aimed toward them. The beauty of this partnership is that you get an enormous surge of pride for them (which often feels even better than self-pride) AND you are building a personal legacy in the hearts of others. That's the legacy that will not be forgotten.