Gary, go for it. Cadman has probably given the best comment here so far on the forces. Ceasar, I suggest you ignore totally, he's just a F&8king idiot.
My SO joined the Reserves in her 40's and she made it through BMQ and SQ so you should make it. She was the second oldest person in each of those courses. The drop outs or those that were RTU'd were mostly young guys. Out of 30 she went to BMQ with, 13 didn't make it. That was four years ago. The last BMQ being run by the reserves here had a drop out rate of about 40%, last summer. Being fit is one thing, but there is a mental toughness you have to have as well. As a reservist, the forces will not send you anywere you don't want to go.Currently there are 130 reservists from B.C. deployed to Afganistan, the largest such deployment since Korea and everyone of them asked to be there. My SO recently came back from her deployment and she's fine with it. Some things did bother her, but we can talk about it because I have also been in the same place, just a different time and war. Holly's client, if he had problems with what he saw, probably just never had a chance to get it out of his system. Some people can't handle that shit, but that's something you have to learn or know about yourself.
If you do join up, and pick a trade in the forces, then you can work fulltime under what they call a B contract. You are employed as a regular soldier, with regular pay and benefits, but as a reservist again you don't have to worry about being deployed anywhere you don't want to go, and that includes within Canada.
So I'd say go for it, if it turns out you don't like it you can always ask to be released.