Visit a shoe store with a pair of well-worn sneakers and have the staff check the soles for your wear patterns. This, combined with your weight and height, will help determine the best shoe for you. Plan to spend at least $70, and replace every 100 miles.

Begin by walking for 30 minutes, three times a week, if you’re starting from scratch. Then slowly integrate running into your workout until you’re running the full 30 minutes each time out. After two months, you’ll be ready to start on a formal training schedule. Download one from nyrrc.org or pick up “The Competitive Runner’s Handbook” ($13 at amazon.com). Marathon-training schedules range from four to six months and require discipline. Yes, eat carbs because you’ll need a lot of energy during your training. Adam Bean of New York Road Runners recommends a diet of 50 percent carbs, 20 percent protein and 30 percent fat. Try the easier races first, like the Marine Corps Marathon in Washington and the Chicago Marathon: both are on flat terrain. During the race, visualize yourself running strong right through the finish line. And remember, if P. Diddy can do it, so can you.