In an interview with Esquire Magazine, former Beatles star Paul McCartney, now aged 75 (as of 2017), was asked if he felt that he still had something to prove. McCartney responded:

Yeah, all the time. And it is a silly feeling. And I do actually sometimes talk to myself and say, "Wait a minute: look at this little mountain of achievements. There's an awful lot of them. Isn't that enough?" But maybe I could do it a bit better. Maybe I could write something that's just more relevant or new. And that always drags you forward. I mean, I never felt like, "Oh, I did good." Nobody does. Even at the height of the Beatles. I prefer to think there's something I'm not doing quite right, so I'm constantly working on it. I always was, we always were. I mean, look at John [Lennon], a mass of paranoia and worries about whether he's doing it right. You only have to listen to his lyrics. I think that's just artists in general.