Lots of lung conditioning. At work I run on the treadmill with a 60min SCBA till it runs empty, lasts 20min under heavy breathing conditions. Would do it in gear for the heat factor, but it becomes smelly and it's a bitch to get it cleaned.. Can't do that at the gym people tend to freak out! Also weight train accordingly for what I do. Dead lift and squat are huge. Power clean is also very beneficial. Only try to work out large muscle groups, legs, back, chest, shoulders. I don't worry about beach muscles, bicep, tricep, and ab work outs are useless excercises in my opinion. Those muscles will come along as you progress.