Your journey with making a game when you have a full-time job?

Greetings!
Luckily and unluckily, I will be starting my first ever job in one week. And for some reason, my flame of making a game has kindled at this bad time.
I have some experience with game dev, I just never committed because I never had a clear idea of what I am making. Recently, I had an idea for a game, it's very simple on paper. Taken inspiration by Fear & Hunger + A fictional book I read.

But I do not know how will I have the energy to do so, and I am wondering if someone has gone through the same thing, how was your journey and what gave you "will-power"?
I had an internship a few months ago, and I barely even went to the gym when it was one of my favourite activates, and now I wonder how can I fulfill my everlong dream when I already have many other hobbies at hand that take less energy to do.