Never quit. But it's ok to take a break!

When you have made up your mind to do something, do it until it gets done. Don’t quit. When things don’t work, take a break and think about what different ways can you try. Don’t try the same way over and over again and expect different results. That’s called stupid! (Or gambling!) Not everything we do in life will end up with something, but if you don’t do anything you will definitely gain nothing.