Train your mind to see the lesson in every situation, and then make the best of it. You don’t learn and grow by sticking with what’s comfortable.
People quit because it takes too long to see results. Because they can’t figure out that the process is sometimes the result. Nothing beats deliberate practice.
The good news is that the sheer act of practicing will help you come out of your shell. The bad news is that you have no other choice if you really want to be amazing at what you do.