I have a friend that decided signing up for a triathlon was the best way for him to get in shape. He started a program of sprint triathlon training that was supposed to take him off the couch to a race finisher in only a couple of months. He spent the first day of his training lying on the side of the road with a cramp and puking his guts out. The good side of the story is that when his training was done, he was able to finish his first triathlon and he has kept up his exercise routine ever since.