Am I too big and too old to be an exercise rider?

I would like to start training as an exercise rider since I love thoroughbred racing a lot and would like to be a part of it. I am 39, 5'10"/175 pds, and fairly athletic - I play a lot of tennis. I started riding at the age of 11 and competed in showjumping in my teens. I haven't ridden much after that, but recently I have become very interested in horse racing. When I do get a chance to ride, it all comes back to me. I'm thinking of applying to the Olds College jockey program in Alberta. I'm from Vancouver. I know to become a jockey you have to be quite small, but is my size ok as an exercise rider? Thanks.