You were a doubter… as in you thought it was normal to sit inside your house the entire day (or for over 12 hours) without going outside at all? Or what?
Yes, some people, particularly coders, are exactly like that, especially when they're young and everything feels like it comes easily. Young coders can sit for hours on a single task if they're really into it and make good progress. As you get older, and the cognitive load increases, you're forced to find out what you did before doesn't work anymore.