And it was much better than I had thought! If you are not quite there yet, the biggest thing that helped me was getting control over my breathing. Steady, deep breaths kept me going and the stitch at bay! At around 15 minutes in my legs started to feel a bit like heavy jelly but after three or four more minutes they lightened up again. Good luck to anyone who is gearing up for the 20 minute run soon. Laura is right- you can do it!