I've been struggling with a lifelong self motivation problem I'm a skilled guy, I can learn anything when I put my mind to it. I've always been a high performe

I've been struggling with a lifelong self motivation problem I'm a skilled guy, I can learn anything when I put my mind to it. I've always been a high performer at jobs I cannot focus on personal side projects to save my life. I have always wanted to make videogames but any time I sit down and try my attention slides off. It's like this with most of my hobbies I'm nearly 40 and starting to feel like I'll never be able to achieve my dream. It's very frustrating because I'm very capable otherwise. I've had a pretty successful career so far. I'm capable when I have external influence I suppose. But self motivation and self starting feels impossible I've read everything about it but I thought I'd throw this out there in case you have some new insight I've never heard before