I am a 33 year old male who is training for an event called the Tough Mudder that is taking place down in Southern Cal. in about 4 months from now. If you are not familiar with this event, it is an 11 mile obstacle course consisting of water, 12 foot high walls, mud, greased up monkey bars, fire, hills, barbed wire, and other enjoyable obstacles. I am in relatively good shape, but for the past 2 months I have been lifting weights about 3 times a week (due to my work schedule) and working on my cardio, plus I've been more aware of my diet. I'm feeling good and seeing progress in my weight training, but really need to improve my cardio. I run about 2-3 times a week only 3 miles which takes about 20-25 minutes. Is it best to push myself to go a further distance than my previous run? Or should I break it up between longer distance running on flatter ground and up hill, more aggressive running? Any help would be greatly appreciated.