How do you know if you made the right choice

So I’ve been looking at my life and things are pretty shitty for me , most days I wake up and wish I could go back years ago to start life once again. Everyone keeps telling me I’ve got lots to be grateful for but unfortunately I don’t feel that way .
Please guys how did you learn to move past decisions you made and not regret it or learn to appreciate life more because I’m in a rot where I don’t appreciate anything.