Ditch the free weights and head to…
Outer Banks, N.C.
If you don't normally consider fishing to be a good form of exercise, you haven't brought in the big catches found at the Outer Banks. Along this stretch of North Carolina coastline, you'll be working your biceps to reel in weighty tuna, sailfish, and marlin. Boat and equipment rentals can be found throughout the OBX, while guided fishing excursions are easy to organize.
Key West, Fla.
Famed American novelist Ernest Hemingway was just one of the many anglers who have flocked to this Florida Key to test their biceps against the heavyweights found in these waters. Snapper and grouper populate Key West's vibrant coral reefs and underwater shipwrecks, and the many deep-sea fishing expeditions operating out of this island's ports make it easy to snag the catch of the day.
Ditch the Stairmaster and head to…
Acadia National Park, Maine
Maine's coastline is lined with trails that will challenge the average sneaker. The craggy cliffs of Acadia National Park will have you working harder than you normally would on any machine or man-made rock wall. But all that exertion won't go unrewarded: Gorgeous views of the park's 47,000 acres of tree-lined rivers, rolling hills, and sandy Atlantic shoreline will take away whatever breath you have left.
Jackson Hole, Wyo.
Visitors to Jackson Hole have nowhere to go but up … the slopes of the Grand Tetons, that is. Jackson Hole sits at the base of many mountain trails, and because it has yet to find a prominent place on the tourist map, the only crowds you'll have to worry about are comprised of bison and elk. When you've finished your daily hike, soothe those sore muscles with a soak in the Granite Hot Springs.
[See: Best Beaches in the USA]
Corrected on 6/12/2012: An earlier version of this article stated that Park City has more than 150 miles of bike trails when the number of miles is actually more than 400.