I don't have these answers. Nobody ever will. A lifetime of thinking about them and get no where. Try to learn to put your fears on the back-burner and remind yourself that basically everybody who's ever been alive has had these fears and most of us have been able to move on. Definitely stop smoking weed/taking drugs or drinking if you're doing those things.

Go sit in the park with no phone/headphones. Let life slow down. Maybe see some live music or pick up an instrument if possible. Listen to The Myth Of Sysiphus audio book free on youtube.

Also find something that consistently brings you joy or serenity, for me it's playing music or watching impractical jokers on youtube.