How to let go? (Mindfulness)

I was diagnosed with anxiety & server OCD at the age of 9. I’ve always worried. Worried about anything & everything which lead to the OCD. How can i let go of fear, & worry & just live in the moment. Not let my worry take over my life because I’ve been living that way for so long. I’m now 21 & honestly I’m miserable 😔 i have so much to be happy about but i let my thoughts get in the way of everything. What can i do to let go and let God? Id live my best life if i didn’t have this problem.