You build on failure. You use it as a stepping stone. Close the door on the past. You don't try to forget the mistakes, but you don't dwell on it. You don't let it have any of your energy, or any of your time, or any of your space.
“No individual is alone responsible for a single stepping stone along the path of progress, and where the path is smooth progress is most rapid.”
“Retiring is just practicing up to be dead. That doesn't take any practice.”