This Summer's Workout Threat-o-Meter
Ouch! Factor: 3, but the soreness might not set in until after you reach your destination.
Stride safely: Matthews suggests a vest, which is unlikely to affect your balance or gait, with weights that are 5 to 10 percent of your body weight (that would be 7.5 to 15 pounds for a 150-pound woman). Bonus: Walking with a vest not only burns more calories but also helps strengthen your bones.
Read more: Bob Green's favorite bone-building exercises