Some of the world's largest marathons are here: Chicago was yesterday, New York and Philadelphia are next month. After seeing the runner's "high" and overwhelming sense of accomplishment participants have when crossing the finish line, you may just get inspired to run one. That's great! Just make sure it's for the right reason -- a love of the sport.

With a record 425,000 marathon finishers last year, many people sign up with a goal to lose weight. However, a recent Wall Street Journal article points out that may or may not happen: "Fitness and dietary experts say marathons increasingly are the exercise equivalent of crash diets, with similarly disappointing results. There's no evidence that running a marathon leads to lasting weight loss."

Some people actually gain weight while training for a marathon. That can be due to myths that you must carbo-load all the time with high-mileage routines. It can be the result of "excuse" eating: "I ran 15 miles today, so I can eat this Big Mac and chocolate milkshake." Or, extra pounds can show up when calories remain high even after crossing the finish line.

While running the actual 26.2 miles is tough enough, the harder part is the months of training. I am now working towards my 11th marathon, and it never gets easier. Each week consists of five runs, hill repeats, speed drills, long runs up to three hours, plus cross-training in the pool and core workouts. The next week, I get up and do it all over again. While different people use different training schedules, it still amounts to a lot of time, a lot of dedication and a whole lot of love for running.

Marathons are a sport where 40 percent of the runners are first-timers, and most of them won't continue after crossing the finish line, according to The Wall Street Journal. People lose interest, don't have the time or don't want to continue investing the time. When weight loss is the goal, the key is to find something you love so you will stick with it.

If you're a veteran runner or serious about just getting started, make sure you have the right pair of shoes.