Can you remember times in your past that made you happy? Lately I've felt extremely depressed about my life and missed opportunities so I grabbed a sheet of paper, pen, and wrote down my happiest memories. I came up with a few things, not as many as I'd like, but it made me feel a little better.
It's never too late. Maybe write down or think about things you'd like to do in your future? This could include volunteering, pursuing a new hobby, and joining a club.
Don't be too hard on yourself either. We all fall in life.
I wish you the best of luck!