...and obstacle race? (like the Warrior Dash, Spartan Race, Tough Mudder, etc)
I've got the running and endurance thing down, but I really lack a lot of upper body strength.
My friends and I are teaming up for a Mud Run. It's 4 miles with a bunch of obstacles (won't know what they are until the day of).

Any tips on how to train for one of these? We are going to run the Warrior Dash next year, but we figured this mud run would be a good beginner thing to do. Typically these things are based loosely on military training obstacle courses, so...