I can relate to that. A couple years ago I went to a summer piano course in a remote place with people I didn't know, and somehow my shy and introverted self disappeared for a couple weeks. I socialized to the point of hooking up with a girl and having another hit on me, without even having to
try. I always had people sitting at my table in the lunch room.
After the course was over I went back to being my old self for a time. But I've been gradually "improving" since, and tending to gradually go back to that state, social, outgoing and self-confident. Except permanently. It's called becoming what you want to be, and it's a lot easier when you've already experienced. It's taking time, but I know by boring/shy self from two years ago is mostly history now.
I haven't hooked up with a girl again since though.

Well, actually I have, but it was the same one so it doesn't really count.
Jam it back in, in the dark.