Right now, I hear a lot of talk about negative things for the economy. The bank bailout can cause inflation and produce the wrong incentives for businesses. People are losing confidence in the economy and therefore are going to stop spending so much, etc. I now modestly propose a fix that would (at least partially) revive the economy.
If everyone picked up triathlon as a hobby, they'd be forced to spend some money. A lot of equipment for triathlon is made in the USA, which helps GDP. Not only is the equipment domestically produced, but also the money spent on races is in turn used to purchase T-shirts, law enforcement, trophies, beer, and food. There's a good Keynesian multiplier effect in this process. Currently, people usually drive an hour or 3 to get to a race and stay in a hotel room, which is good for the city in which the race is held. However, if everyone adopted the sport, then the density of demand for races would increase and each town could have its own race, reducing the amount of fuel consumed in order to get to a race. Speaking of fuel consumption, more people would be commuting on bikes to fit training into their busy schedules. This would produce a lower wear on the road system and we wouldn't have to spend nearly as many resources repairing roads. Road work is costly for a few reasons: 1. it slows drivers down when it's happening. 2. it uses up scarce resources. 3. it doesn't add anything that wasn't there before (like building a new road would do).
Another effect of widespread adoption of triathlon is that people would be healthier on average and they would require less health care. Health effects can be realized in a short amount of time. There's a kid on the FSU team who lost 10% body fat over the summer. Also, triathletes are less likely to smoke than the general population. Between smoking less and driving less, they are imposing fewer negative externalities on the rest of the economy.
It's better than eating your children.