I agree that taking a class makes boring body weight exercises a lot more fun. Another thing to consider is to run your sprints and in between, do some pushups or squats or planks or something like that. You could also force yourself to clean your house better by moving the furniture around when you vacuum. You could pick up a rock like Knifgill does or do the sandbag thing. Flip a tire in the back yard maybe? I know these things sound pretty boring to me, especially the house cleaning. Rock climbing is pretty boring because you have to spend so much of the time NOT climbing. You could try trail maintenance, you know, cutting bushes with saws and loppers, repairing tread with a McCloud or doing rock work. Lots of volunteer opportunities available depending on where you live. Check the local weekly paper and see if there are any crazy classes you could join. Hell, maybe even a drum circle would do something for you. Bang on a drum and dance the night away.
Female, 5'3", 48, Starting weight: 163lbs. Current weight: 135.
Starting squat: 45lbs. Current squat: 145 x 4.