That's true, I am kinda nervous to try it because you're supposed to hyperventilate really hard and then not let your SI take over as you drown in water. Honestly I'm just terrified of getting some kind of damage if I fail. Hyperventilating might also freak me out, make me panic and put me in survival mode, I am not sure at all tho.
Well, there's some mammalian reflex that I heard somewhere on this site, where if you stick your head in cold water it'll calm you down. If I tried I would use hot water to get me light headed, but cold water might be your best bet.
The other thing, I heard from watching a YouTube video by Vsauce (if that's spelled correctly) about holding your breath. In the video he said never to hyperventilate before going underwater because hyperventilating gets rid of carbon dioxide, while still having regular amounts of oxygen. He said that that way you'll end up drowning without even feeling like you're drowning. You might not panic that way.
As for damage, I have no idea. Maybe water in your lungs is bad, but I feel like the worst thing possible would be someone "saving you" after parts of the brain loose oxygen. Maybe you would end up with something like a stroke, but I don't think that could happen if you're sure nobody will pull you out. Also, that's just a complete guess.
Maybe you should try something new though. I had been feeling better about my life after having joined my school's anime club, and you don't have to be in a school to join a club either