Also see: Failure
There's no need to take mistakes personally. See them for what they actually are: indicators on where we can improve the program.
What if there were no mistakes?
If you could zoom out far enough, you would discover that your entire life has already occurred. Visualize the life of a spider you just killed. From your perspective, from the moment you saw the spider until the moment you killed it, you just viewed it's entire life. From your time-space perspective, it may have lived only as long as it took you to find something to kill it with. From it's perspective, that time was a lifetime.
Suspend disbelief for a moment. Whether or not you possess these beliefs, try them on and see if you world improves. They'll likely be very subtle improvements, but that's how change happens - one increment at a time.
Our start & end dates are predefined. From the perspective of a future time, your life has already is already over. You can't stop worrying about when you're going to die because it's not up to you. Your demise is eminent. What's less certain is your quality of life as you age, and for that reason, taking care of yourself is worthwhile. Inactivity combined by a poor diet is more likely to make your later years in life less enjoyable. Take care of yourself, but don't worry about how it's going to end.
Trust in the perfection of the moment. There are no mistakes. Nothing that's ever happened has been a mistake, only our judgement of it being so. Our existence is an evolution in realizing our potential. We are always at our full potential, yet our full potential is never fully realized. What I mean is that we are all doing the best we can from where we stand. Recognizing an opportunity for improvement is the first step to realizing that improvement. Our potential is perpetually expanding from moment to moment. We're better than we used be, but not as good as where going get.
Our full potential will never be realized because by definition, potential is indefinite.