Difficulty Meter Like biking uphill—in third gear

Whitewater, Wisconsin

• Drive Time 2 hours

The growing sport of fat-tire biking (or simply “fat biking”), which involves outfitting mountain bikes with snow tires at least 4.5 inches wide, has made its way to Kettle Moraine State Forest and the 30 miles of biking trails in its southern section. Backyard Bikes and Ski will outfit you with a bike and helmet ($45 a day, backyardbikes.com) and give you a five-minute lift from its shop to the John Muir Trail, a wooded fast track with multiple loops, steep-and-deep climbs, and tight switchbacks. Winter does have its advantages: “If you fall, you land in snow,” says Mike Bettinger, owner of Backyard Bikes. Plan your outing by time, not distance, since a two-mile ride through a powdered, rolling forest is a lot slower than a two-mile ride on pavement. The wind won’t be much of an issue, though. “As soon as you enter the woods, you don’t feel it,” he says. “You’ll just see the trees rocking back and forth, which is pretty cool.”

The Particulars

Body Burn Quads, glutes, and arms.

Stay Drive 25 minutes to Lake Geneva for the 349-room, lakeside Abbey Resort (from $119, theabbeyresort.com), which boasts an ice-skating rink with free skate rentals for guests.

While There Let the massage therapists at the Abbey’s 35,000-foot Avani Spa work out sore muscles ($130 for the 50-minute Fire and Ice massage) before leaving you to relax at the adults-only pool.