Welcome to CrossFit: Forging Elite Fitness
Dont need to go overboard, check out some of the exercise demos and use your imagination. Do your work outs around their 3 fundamentals, Functional Movements (use it or lose it), High Intensity (no rest in between) & Constantly Changing. 10Burpees, 20situps, 20 pushups, 5 pullups as many reps as possible in 10mins (FAST). Do it twice a day if you want and wear your pack or bodyarmor when you are ready for the added weight. Run 5km as fast as you can once a week. Train 2days/1 rest then build to 3days when you feel ready (1:1 could be considered maintanence, 2:1 is slight improvement, 3:1 is good. Rinse and Repeat. There's no shortcut, condition your body (and feet) to get used to carrying weight... Hike/pack march for 6-8hrs, 2-twice a month, resting for 10mins/hr. Carry a 5kg weighted bar if u cant use your rifle. hope it helps.