To anyone who is training for one, I strongly suggest, drop the cardio and get strong. That's what you really need.
The obstacles I truly hated, and just because of those I won't do a TM again, are the ones that include electric shocks. I don't get it; I don't know what they are meant to prove. It's painful, and it doesn't test or challenge your strength or stamina. Can't train for those. Ugh, hated them.