Not talking about seklf-help books for depression, anxiety, or any other sort of condition but just regular self-help books that masy help with social ability, success, etc.

Which ones have helped you the most?

Learned Optimism by Martin Seligman
The Seven Habits of Highly Effective People by Stephen R. Covey
A General Theory of Love by Lewis, Amini, and Lannon
and many others