I would say a different mindset would be focus on your progress. It might help to make recordings of yourself and look back to see how much you have grown. Something that may help with practice too: take a small section of the song and play it slow enough to play it perfect. Once you can play it slowly but perfect, then speed it up little by little. If you are performing, still make time to rehears the whole thing (but focus on performance rather than perfection.) Then after the performance, work on perfecting again.

It takes a lot of patience, but the others are right; speak positively to yourself rather than worrying about mistakes :) Keep it up!