I started out with a simple phrase that I first got from a book I'd read;
'Everything is unfolding exactly as it should'
You don't even need to think that's because of God or any divine plan. For now, you can just offer it to yourself as an assurance when you find yourself worried or anxious or feeling the need to control.
I would say that phrase to myself and then choose to let go. Sometimes I'd have to use it dozens of times in a day - but gradually I began to see that it really did work. And that helped me trust in it, and that led to MORE!!