I like this thread, so i'm Brett - 31 and have been in and out of riding trials since I was 14/15 (so a 90's boy).
Personally, sod it, if the body is willing and the mind is able, then keep going.. I am 32 in July and currently building a 24" bike and planning on getting a new DH bike later as well. So it will be a year of keep riding cool bikes badly!
Over the years I have been in and out of love with the sport, but I always keep coming back and I love the huge increase on people rebuilding older style rigs. Makes me reminisce over the days when baggy jeans, beanies (instead of a helmet) and key chains were an acceptable part of trials fashion, when square taper cranks were being removed with a crank puller and a 5p piece, when Armstrong cranks that flexed were fine and when a trials frame was 12" /14" seat tube... I could keep going
I digress, keep riding until you can't do it then hang up your wheels and get involved in something like fly fishing