Join Date: Aug 2009
Location: New South Wales, Australia
You see riders in eventing (even at the high levels) with ages ranging from 20 - 50.
It will take time to learn to ride, but I don't think you have to start when you are five, or very young at all.
If you get a good schoolmaster and a good instructor I think you will surprised with how quick you pick up riding, especially if you ride daily. I wouldn't recommend starting at 35 to become an eventer, but I can't see why someone entering at 25 or something couldn't have a shot. You have to work it though.
I think a lot depends on the individual, on circumstance and opportunities around them.