Build sprints into your program to increase overall speed.
Get out for a run or fast walk at a pace that allows you to hold a conversation. Start with 40 minutes and work up to an hour. Ten minutes into your run, find a long, steep hill or staircase (something that takes at least 30 seconds to ascend) and sprint up it. Power uphill six times, walking back down. Finish your workout with a five-minute cool down. According to The American College of Sports Medicine, intervals burn more fat and help keep it off better than steady plodding. More important, they increase your speed on the trail, which translates to more ground covered and new territory explored.