Start doing core exercises. I threw out my back when I was 24! Now I'm good because I lift. Deadlifts are magic. Also over the years (16 tattooing) I've learned it's about the art, but it's also not. It's mostly about people. I've worked with artists that don't get this and they're really cringe. We don't have a job without the people we tattoo, they aren't disposable and should be treated with respect, always. But also stay firm with your own boundaries. Have fun!