From somebody who doesn't train for this, get into shape to run a lot. Also get some massive hand and arm strength. The way they accomplish the 10-12 mile courses is with a lot of back and forth in an area. If you can have your body trained for running distances, you will be in great shape. The hand/arm strength is for helping to haul yourself around. The monkey bars and monkey rings can be a challenge. Climbing over walls means pulling yourself up to get over the top.
In Seattle this year, the monkey rings were slick. I can normally hang on without issue, but on the third of about 5 rings across, my grip wasn't hard enough. On the monkey bars, you start by going uphill on them which takes extra effort. After I hit the peak this year, and started going back downhill, I was skipping bars, and right before I could get my feet planted on the far deck, I lost my grip.
As I was approaching the last few obstacles this year, I passed a guy who was probably 300+ lbs and still walking along. Remember that if you need help from others, ask for it. If others ask you for help, then give it.