Have you maintained high fitness & strength now you have left? If yes, how?Regarding fitness, in addition to what le Caporal posted, think agility. To run an obstacle course well you need overall strength. To climb up the side of a cliff you need to be lean and have good arm strength. When parts of your body start cramping from the cold your other parts should keep you going. Swimming muscles aren't the same as running muscles. Swimmers are usually longer muscled..and you should be able to hold your breath while doing stuff for at least 1 and 1/2 minutes without double extending. One of my personal training points was that if I punched you in the ribs I would break one. I also could take a punch. But if you want to be more capable, you need to be fast and accurate with your strikes with whatever part of your body and with whatever is at hand. Look around to see who the best are and try to match them. You can't do everything but you can be in the top 15% overall.