'I want to proof myself', 'I want show them they're wrong'... These motivations can be helpful for a short time, for example to start a goal. But it's not a sustainable motivation. And honestly, I think they're even damaging that increases risk of injuries.
When I realised I'm running for myself at the third round on Antarctica, because it took me to unique and beautiful places everywhere in the world, I noticed that I do what drives me. It made me smile, it was contagious. And I realised: when I run with this smile, this sparkle in my heart... That is my right motivation.
No proof, only for myself