To get started, you download an iPhone app that lets you check in and check out of a database of gyms (and you can add your gym if it’s not already in the database). Then you set your pact for the week, telling the service how many days you want to workout and for how long and how big a monetary penalty you want to charge yourself for failure. Over the course of the week, you do your workouts and your check ins. If you don’t show up as often as you promised yourself, you get penalized. If you hit your target, you get a reward paid out of the revenue pool generated by the failures. GPS tracks whether or not you’re actually at the gym, and payouts are proportional to the amount of time you commit to so there’s no way to earn big bucks with comically lax exercise goals. It’s a quick and easy way to pre-commit yourself to meeting your goals, and make it less likely that akrasia will undermine you.I’m a little skeptical about the prospects for this for reasons the article gets in to, but note the power of GPS integration here. The basic concept of a precommitment device is well-understood and the software behind GymPact is hardly earth-shattering, but the fact that a large minority of the population now regularly carries a pocket-sized location-tracking computer around with them all the time lets you employ a lot of old ideas in interesting ways.