First things first: stop trying to please other people. Be who you want to be without any pretenses. Next up you need to learn to say no. Say what you mean and mean what you say. Remember to grant yourself permission to make mistakes but it’s important to learn from them. Perhaps one of the most important ways to overcome lack of self-belief is by helping others. Nothing in the world will give you the same personal gratification as the one you get from helping someone.