There is a saying that "the candle that burns twice as bright burns half as long." Well, yeah, that's true. But if we look at the analogy, we can see that there are more than just those two qualities involved. How big are the candles? If a candle burns twice as bright, but is also twice as big, then it will burn the same amount of time.
To apply this extended analogy to people, it still holds true. Sure, everybody burns out eventually, but some people can do more than you and do it for longer. How is that possible? Well, they must be a bigger candle than you.
Frustrating though it may be, we're not all made equally. That doesn't mean you shouldn't try if you aren't the absolute best of the best. It just means you do the best you can by giving your all. Choose the amount of energy you wish to exert and know that you will burn out faster by burning brighter, and that it has nothing to do with how bright or for how long other people burn.