Believing yourself is a habit like anything else , a habit of the mind. It won’t happen just yet; it's one of the by products, not the end in itself. Even the most successful people struggle with self doubt. I’ve realized that I need to learn to handle my demons and make them work for me, not try to vanquish them.
It reignited me and made my past irrelevant. You can’t betray your purpose and your dream — if it’s genuine — cannot be broken by anyone including you.
So begin with a stoicism journey and find your purpose (there is a journey for that too) afterwards.