I've done it before, sort of. Thing is I dont have a FIRST job. So, uh, the concept is a little bent, but you get the idea.
In my case, it's typically related to game design and/or testing. I dont do it professionally. And I sure dont do it all the time. But every now and then, the opportunity presents itself, and once I get started on something... like REALLY get started on something... I'll approach it obsessively. I also review games on Steam (and yes, my reviews get a LOT of attention) and that's a whole other type of work.
The one issue I found though is that it's easy to get burned out, and THAT doesnt help. Like, I've mentioned the game I helped make, right? I've no idea if anyone remembers that. But I did it, it was contracted work for an indie dev, and it was pretty intense. Not only a lot of working on the game, but I also had to play it. A lot. Like, A LOT. And then came the expansions after. Even more to make and even more to test. And due to the nature of the game (heavy amount of prodecural elements) this made the testing extra difficult.
And when it was all said and done... I didnt want to so much as look at the bloody thing for MONTHS. Which is still stupid to me. That first time of achieving a childhood dream and REALLY making something, and the process of doing so burns me out to the point where it's quite awhile before I want to go near it again.
So... yeah, be careful of that. It can happen to anyone. Working on something like what you want to do is great and all, just... dont push it too much. All good things in moderation or whatever the saying is. Is that even a saying, or did I make that up just now? I dont know.