Do it with a team or find a partner!!

You are more likely to stay strong to the end when you run in a team. 

Be sure the others on your team are at your same level as you are.

Ideally don't have a team of more than 4 or 5 members. If your team is too big, you are more likely to wait for some people, and lose momentum. It can also lead to sore muscles and hypothermia if you wait too long in the cold. 

Create a team costume for fun!