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Surfing Exercise: lots of it

What you burn is governed by the specific wave conditions and height at which you're surfing. The average beach runner spends two to three hours out on the street and back, and a Pilates studio enthusiast spends about 10 hours a week practicing. Those figures might not seem like a lot, but they add up, and when you're paddling through waves, taking in the scenery and memorizing that handlebar-mounted lever instead of your usual handheld computer, you start adding up.

Surfing is easy: the sport is a full-body workout, and you can spend a morning at the beach in little more than running shoes. However, hitting the trail is more demanding, requiring the kind of muscle and cardiovascular conditioning you'd get on a trip to the gym. Running, biking, swimming, paddling, jogging, crisscrossing the backcountry: it's all on the books for as many as 500 events a year for three avid enthusiasts. Quantifying your lifestyle reveals how much you spend on activity — and how much it costs in effort and stress. Those costs (plus some happy hour expenses) will add up if you count some personal gains.

You can get into that perspective even on a walk — the likelihood of a single-day park outing equaling the sum of two full-week jogs is a vanishingly small one. It's less true when you're a solo act. For one Appalachian Trail enthusiast (starting at Kettle Creek, Maine), recording 110,300 steps on a midwinter hike to Mamont, Ore., meant spending a gruelling 15 hours just to log the miles he should have.

Using yourself as a kind of quantified-self test, you can use these numbers to measure and improve your health and quality of life. When you know your lab results, you can monitor your progress and even tweak your training program if you're falling behind. It's easy to say you're hitting your walking stride, but looking up weekly totals will show you just how much you're doing wrong.