Do you promise yourself you’re going to workout and then reneg on the promise? Have you ever bought a gym membership and stopped using it?

The GymPact app assigns a real cost to the common practice of skipping trips to the gym. Users who resign themselves to this app’s clever premise must pledge a certain number of weekly gym visits (at least one), each for a certain interval of time (at least 30 minutes). The financial penalty for dodging a workout is likewise self-determined, but the minimum is $5—a decent sum, especially for those who follow a strict gym-skipping regimen. Geo-location confirms when users arrive at the gym and the amount of time they spend there. Regular gym-goers not only avoid fines, but also reap financial rewards—from the pockets of their lazier counterparts.

Pretty Smart, huh? Do you know of other apps to help keep you on track?