Music.

It can give strength to the weak and funk to the previously funkless.

And even more impressive, it can get you through a three-mile jog. Provided you’ve got the right playlist...

Introducing Jog.fm, a site connecting you with playlists calibrated to suit the intensity of your workout, online now.

Think of it as the musical equivalent of a grizzled-but-tuneful track coach—providing just the right amount of motivation to get you to the finish line. The first step is to type in your average mile time for running, or your RPM for biking. (You’ll need a stopwatch and an extremely dedicated friend.)

Then the site will convert the mile time or RPM into beats per minute, and connect you with a flock of user-created, iTunes-ready playlists about as long and exactly as intense as your workout.

So when you’re struggling through the last leg of a certain Northeastern marathon, and you need the juice to speed past the Kenyan warhorse just a few paces ahead, you can count on Eddie Money coming in to save the day. The site’s still working on auto-generated playlists with warm-up and cooldown periods, but in the meantime you can make your own—maybe even one with an unexpected boost of energy around the 12th mile.

And by energy, we mean Swedish disco.