Relax however you can at the end of it, get your mind off it, enjoy your favourite hobby, don't think about it. There will always be bad days, for everyone in the world. If they don't kill you, just keep on going and look forward to the next. For me, and this is even more in regards to work than stuttering, I try to purely think about things I like, such as my hobbies. If I get pissed about something at work or criticized or embarrass myself stuttering, the pain is only in that slight moment, and I go back to thinking about things I like. You've got to control your own reality. Need to develop a "well, that sucked, moving on" attitude.