The Boston Marathon starts in Hopkington, Mass., and ends in Boston, but one of the most famous portions of the race is Heartbreak Hill. Nestled in the quiet town of Newton, Mass., Heartbreak Hill is an 0.4-mile ascent between the 20- and 21-mile marks near Boston College.

Olympic distance runner Mark Coogan is no stranger to Heartbreak Hill, and he joined Jenny Johnson on the marathon route to give some insight. Check it out in the video above.