I'd like to run a half marathon. I don't know where or when a local one might be, and I don't know how to train for one, so these are things I'll have to research. But I do know that Lance Armstrong ran the New York Marathon in about three hours, and I can run six miles in about one hour, which means I can probably run 12 in two and a half to three (assuming I'm gradually slowing down). In comparison to someone with seven consecutive Tour de France victories, I think this is respectable.
Step one (get it? step?) is going to be getting in the car and measuring out some mileage. Step two is buying new running sneakers (to avoid shin splints). Step three is going to be a test run (ha!) to see how far I can go before I feel like dying. And step four will be to then research an actual training regimen. With luck I'll be in full training mode by summer, when the weather is nice and classes slow down.