What happens if you run in front of a car?
You get tired.
Why can't tomatoes ever beat lettuce in a race?
Because lettuce is always a head, and tomatoes have to ketchup!
What did his wife give the guy when he came home all sweaty from his run?
The stink eye.
What do you call a free treadmill?
The Great Outdoors.
Why was the marathon runner plucked out of the race and taken away to jail?
For resisting a rest.