Once you've gained confidence by retraining your brain you'll have a new chapter of your life.
When you lack in confidence you may feel anxiety, so to get you started in becoming more confident, start with the small things you want and possibly need to do. Such as going to the shop for food.
Before you go on a small trip somewhere, when you'll be out of your comfort zone - where you feel safe and where you have feelings like you don't deserve fun things like a trip. It's time to let go of these thoughts and feelings by saying to yourself while you look at yourself in the mirror: "I deserve to enjoy my life and have fun when I want to". This will you the inner strength to hold your own confidence and to be proud of yourself for having self-confidence.
You'll feel that it's exciting to step out into the world and to have some fun.
Let yourself have curiosity and love for your new feeling(s) of freedom and you having fun a lot of the time.
Once you've gained your self-confidence in yourself, you'll feel it's time to live your life your way.