How many of us have quit something because it was too hard? Or because it hurt us, either physically or emotionally? How many of us have quit something we enjoyed because we were told there was something wrong with us? How do we know when it's time to give up?
The answer to all of those questions is it's not. I've read and been told that there are no failures, only new expectations. Quitting and not trying are the only way you fail. Quitting is a sign of weakness.
Blah. Blah. Blah.
I've heard so many things against quitting that I've begun to tune them out. The problem is they're right, to a certain extent. Quitting something before you've really given it a chance is, in my eyes, the only failure there is. If things don't go your way, then find another way to make it happen. If you can't, then change your goal or actions to accommodate the new parameters of the situation.
That doesn't mean there aren't times when you shouldn't quit. Self harm is something that you should quit. Harming others to make yourself feel better is something that should be quit. You should quit abusing someone. These it's not a failure to quit but a necessity. Though with these, a lot of it comes down to perception, a sense of worth, and the willingness to make the changes.
If you want something, don't quit. Find a way to make it work. If you absolutely can't, shift your view until you find what is working and follow that. Follow the positives. Follow the accomplishments. Look on the positive side of things and find reasons not to quit.