Running a marathon is about more than just crossing the finish line. Training for a 26.2-mile run can help increase your endurance, strengthen your heart, and build muscle. The training process can also reduce stress by producing endorphins. The experience of training and completing a marathon simply can’t be beat: not only will you get in great shape, but it can also be an opportunity to support a charity, get out of your comfort zone, make friends, and inspire your…