Running a marathon takes serious fitness and dedication, and we can only imagine the feeling of relief and pride you feel when you cross that glorious finish line.
The last thing you want is to not cross it at all, and an Irish fireman at the Boston Marathon is being called a hero for his selfless act in the last leg of the race.
Many runners were suffering from the high temperatures at this week's run, with one woman's legs completely giving out from underneath her.
Two men, including fireman Terry Canning from Northern Ireland, come together to help her cross the finish line, with the Irish man eventually lifting her up and carrying her across.
Julie Bowe told ABC News that she was so thankful to Terry for helping her cross the finish line.
"The fact that he was that close to the finish and he was willing to sacrifice some time on his race to help me is incredible and he's just said things like, 'You know I run many races, just stay positive, hopefully the marathon will treat you better next time,'" she said.