Oops, my bad!
Sorry about getting your gender wrong. I, of course, have no experience with more female oriented products since I am a man.
As far as what causes it...couldn't say. Everybody is different. I've never had a cause pinpointed and have gotten answers ranging from stress or depression to MS (luckily the MS turned out not to be true). Today I've got a lower back MRI as I also have pain symptoms. My neurologist thinks that the leg pain and incontinence could be caused by something there. There are exercises called Kegel exercises that have helped many people (but again, not everybody and I think it may depend largely on what is causing this for you).
Your age should not be an issue. Age does not cause incontinence, though sometimes medical conditions that can come with age may. Though at your age (or mine at 32), it should especially not be a problem.
Do you have children, especially recently? That can be an issue for some women when it comes to incontinence.
Bottom line though is that it's impossible for me to say. I'm not a doctor, and even if I was, this is just an internet message board
. Remember though that no matter what, incontinence should not stop you from doing anything. As you can tell just from this board, there are a bunch of us out there of any age who manage to lead normal, active lives!