You're going to stop worrying about things that won't happen. Don't happen. Which includes just about everything you're anxious about.
You're going to stop seeing the future as a dark depressing place you don't want to visit. Come what may, you aren't always going to feel like this. I promise.
You're going to stop trying to lead other people's lives for them. Let them make their mistakes. It's the only way some people learn.
Worst case scenarios very rarely happen. Every adversity carries with it the seed of a greater benefit. That which does not destroy you makes you stronger. Yes, all the old clichès are true.
'Once upon a time
Before I took up smiling
I hated the moonlight.
Spirit of the night
That poets find beguiling
Seemed flat as the noonlight.
Once I awoke at seven
Hating the morning light.
Now I awake in Heaven
And all the world's alright.'
(Rarely sung prelude to Blue Moon).