How do you recover mentally after a terrible contest?

I've seen people suggesting to stop caring about rating, and that rating is simply "meaningless internet points", but it's rather hard to not care when you watch the results of your efforts crumble away due to your own incompetence. Perhaps my performance is shit because I am shit, and I've simply been lucky to have performed better thus far. It sometimes hurts to even look at some contests' problems because of the pain they've inflicted upon me.

How do you deal with these feelings?