Gabby Logan looks ahead to 2018's London Marathon and meets some of the runners. Over 40,000 people will run the 26.2 miles, and each has a special reason why they are running. From the world's best elite men and women runners in Eliud Kipchoge and Mary Keitany - who are aiming to set new world records - to the fun runners who are raising money for many charitable causes, the London Marathon is a global event that brings people of all ages, abilities and backgrounds together. This programme meets a range of people who make it such a special, inspirational event, including Sir Mo Farah, who is running the full distance in London for only the second time, and Kathrine Switzer, a pioneer of global female marathon running.