I am 48 (and I'm also female - my username is Jespah, not Joseph).
I have had some in my teen years but they got more frequent in the last, I think, 5 or so years. I have also lost a lot of weight in the last 3 years (about 140 lbs). That may be related.
Vasovagal pretty much means a generalized form of unexplained fainting spell. Technically, it's a correct diagnosis, although it's also something of a copout. It's kind of like calling sniffles a cold. Well, yeah, it's a cold, but which type?
For me, I drink water. Lots of it, but also am mindful of the fact that too much water screws up my electrolytes and will also bring it on. For swimming, I bought ear plugs, and I still mainly try to swim with my ears out of the water and that helps. I also stop swimming when I feel myself getting too tired. Getting overly fatigued can help bring it on, too.