Perhaps take up fitness/exercise. If you look good you feel good and confident too.

Like the previous poster said, trying to do everything right at once can be difficult, so yes, just start with one thing.

When you do one thing right, you get more energy for other things. And when you do two things right, you feel better and can do other things better. So that's a sort of upward cycle.

I've been a bit depressed lately, and I've taken up exercise. Seems to work.