Looking for a book about a real underdog who turns their life around

Hey everyone, I’m looking for a book that tells the story of someone who starts off as a total failure—whether in career, relationships, or just life in general—but manages to turn it all around and achieve real success. I’d love something based on a true story, but a well-written fiction book could work too. Ideally, it should focus on resilience, lessons learned, and the struggles they had to overcome. Any recommendations? Thanks in advance!