There are some days when I pick up my guitar and I am just rubbish. I can't get anything right and I want to throw the axe out of the window. I would have given up by now if it was not for the advice I got off a fellow workmate who plays and has a band.
His advice was simple 'You will pick up the guitar and play like a god most days. On the other days when it all goes wrong.....just put it down and come back later'.
That has helped me more than he knows. It was simple but effective.