“If you’re new to exercise, walking may be a great way to start your exercise program.”It’s all about the intensity of your trekking. Pay attention to your heart rate, Thein-Nissenbaum said. If you can talk but not sing while walking, you have likely reached a heart rate that qualifies as moderate exercise. Increase your heart rate by speeding up your pace or adding hills to your route. Fartlek is Swedish for “speed play.” To do a fartlek, mix easy walking with short bursts of faster walking.