How did you get into Garry's Mod?

What got me into Garry's Mod? To be completely honest I'm not quite sure, I got as a birthday present from a Humble Bundle pack some-odd years ago, didn't play it for a week or so since I had other things to do, it took me a bit to get into what the game was about, which is just to be consisting of at least 400 addons and friends.