If you miss the 13:50 flight I would agree that the downtown is too far away.

However you could get to a gym to work out at for an hour or so and have a shower. I use Monster Gym at 40 Ronson Drive (416) 243-2503 it is a very short drive from YYZ about three to five minutes. They have a daily fee for non members of about $5. You will feel great afterwards.