You love your gym for a number of reasons: it's conveniently located; you always leave feeling refreshed after a long day; and, just admit it, you like being among the toned bodies. Ah, but here comes summer full of sunshine and warm breezes, beckoning you outside and away from the air-conditioned warehouse you call your second home.

Just because you're trading gym time for blue skies doesn't mean you have to give up trying to be a hard body. In fact, there are many outdoor activities that mimic gym workouts while yielding added benefits. Trees, mountains, rivers and lakes will revitalize you in ways that wall-to-wall mirrors can't.

Clyde Soles, author of the book Training for Peak Performance knows this all too well. "While elliptical machines, treadmills, and spinning bikes are OK if there are no alternatives, getting outside is always better," Soles says. As a prolific climber and expedition leader (as well as the founder of Trail Runner magazine), Soles has perfected the outdoor fitness regimen.

We asked Soles to name five favorite activities that would keep anyone in shape outside of a gym.

Power hiking
No tiptoe through the tulips here. Rather, "aggressive hiking with trekking poles to get the heart rate up for extended duration," he says. If you live near hills, all the better, though elevation gain is secondary to keeping up a brisk pace. Step it up a notch by donning a stuffed pack. It's also a good idea to wear solid and supportive hiking boots or shoes to avoid foot injuries, and bring lots of water.

Trail running
"Trails help improve balance and stamina better than roads and have better scenery," Soles says. Running on trails away from cars and bikes reduces the likelihood of nasty collisions, plus the solitude can be a refreshing change of pace. Most leading shoe companies now make models specifically for trail running; it's a good idea to invest in a pair.

Snowshoeing
OK, it's not a summer activity, but in many parts of the country, snowshoeing is possible in the buffer seasons of spring and fall. You may just need to drive to a mountain pass. In winter, if snow covers the earth where you live, you can showshoe right out your backdoor. The added weight and drag of the shoes makes for a hearty workout. Use trekking poles to add extra balance.

Road biking
"Low impact and great cardio rolled into one," Soles says. "Road biking is great for long, steady aerobic conditioning," Even better-you can ride your road bike to the gym if you want the sun and the mirrors. Be sure to wear a helmet and ride with traffic.

Rock climbing
Rock climbing isn't so much aerobic, but "long, moderate routes promote endurance and fine muscle balance-plus give a mental boost," Soles says. Few activities provide adrenaline rushes or natural highs like climbing. A good place to start is an indoor rock gym. Once you have the basics down (climbing technique, gear usage), take it outside-where it belongs.