I have a very similar training regimen. I train twice a day. Morning and evening. What I do depends on how I feel and weather. It comes out to probably 14+ hours a week. I either do weights (squats, cleans, etc) or run or walk with a weighted vest (40 lbs at the moment) for 3 miles.

As long as I eat and sleep enough I feel awesome and have tons of energy and mentally I feel better. In fact, I felt better mentally and physically when I started doing 2 a day workouts.

Everyone thinks I'm insane and say it's not possible without drugs. At first it might make you feel a little drained, but you build up to it over time if you stick with it.

The human body is capable of amazing things. You don't have to treat it like a thin shelled egg when it comes to exercise.