Interesting to see a thread like this on osu! I don't have any interesting story to share though. I've been athletic pretty much all my life, competitive swimming from age 8 all the way through highschool, then started lifting and its been a little more than 2 years now though I have taken breaks sometimes lol
But here's some very general tips for guys who are just starting/want to get into lifting, because I think there's a few of you here xD
1 - Don't feel shy, nervous, intimidated, whatever just because there's a lot of big guys there. This is actually a huge reason why a lot of people don't want to go, but it really makes no sense. Everyone was skinny (or fat) at one point. In fact, most people at the gym are happy to start conversation or help you if you ask!
2 - Start light! Just like how in osu you have to start on easy beatmaps, lifting you have to start with light weight that you can be confident with. Try to develop the proper motions for the exercise to feel natural before moving up weight, which brings me to the next point
3 - Practice the proper technique for your exercises. Getting a good workout is all about ripping up the right group of muscles, not about how much weight you can pretend to lift. So if you can't go all the way down on a bench, don't cheat yourself by going halfway! Drop the weight and try again
4 - You might feel like shit the day after, sore and everything. But I guarantee after 1 month or so lifting will feel great, you won't even notice the soreness and feeling swollen big after a workout is just great!