I took ds7 to ballet when he was 3.5 and becoming reluctant to try new things. It was great because he was the only boy and the girls were more compliant - at gym there were always at least two boys off task or misbehaving.
Your son had a very different dance class than my DD did. Though I'd have only labeled one girl as a behavioral problem, none of the kids were paying particular attention to the instructors except mine. That had always been one of the traits that marked her as exceptional early.
I also took up the Violin after Aiden and let him teach me some things, and now we often practice together.
I took up the guitar after my DD did, but that has worked out less well than I'd hoped. On one hand, DD gets to see me mess up, keep trying, and exhibit a growth mindset. But... DD exhibited task-avoidant perfectionism when she took it up. And I didn't take it up strictly to help DD with her perfectionism; it was a genuine interest of my own, and being able to share it with her was a bonus. So, given that I was genuinely interested, approaching it with a growth mindset, and coming at it with a far greater grasp of musical theory, it should come as no surprise that my results have been superior to hers.
The takeaway I'd hoped she'd get from that is how the growth mindset pays off. I've backed that message verbally, as well. But it's obvious that I'm still competing with her notion that, "Dad is good at this, I am not." So that's a lesson learned. It probably would have worked out better from a perfectionism standpoint if it had been something I'd have been less interested in, and been more willing to allow her to be the teacher.
Still, progress is being made on her perfectionism, and since I'm coming at that with a growth mindset as well, it's all good.
And here's where I confess to being an underhanded manipulator. DD and DW are currently out of state visiting family, and DD took her guitar. At this point she's VERY fluid on individual notes on the bottom three strings, because that's her comfort zone, and her perfectionism stops her from pushing past that. The night before she left she gave chords another whirl, went through the usual process of saying she hated them and couldn't play them, but this session ended with two chords that sounded good. I told DW about the minor breakthrough, and suggested to her that
someone could encourage DD to work on those two chords for the better part of the two weeks before I meet them on their vacation, so DD can
surprise me with her sudden progress.