So being out here on the trail, I've been forced to think of alternative workouts to the usual gym workouts with gym equipment. However a full body workout is easy is the type of supplies backpackers usually carry. For your legs, if hiking isn't cutting it, you can try body weight squats. If that's too easy, try em with your pack on, that's about an extra 40lbs. If you need more weight, fill all of your water containers. Remember, water is heavy. For an added challenge, try a squat while holding your pack over your head. For your chest, if good old pushups aren't good enough, add some resistance and try doing pushups with your pack on. You'll be surprised what a big difference just a few pounds can make. For an added challenge, if you have a rope, throw it over a sturdy bramch and you have an improvised suspension training system. You can tie the rope into handles, or just wrap it a few times around your hands. For your back you can do chinups and pullups of low tree branches. You can also do one handed rows using your pack. Once again adding or removing water to change the weight. You can also use the rope again for supine lying pullups,rows, and curling. For your shoulders you can use a food bag or stuffsack with some extra weight, once again using water to change that. And doing lateral raises. A backpack is good for one handed shoulder presses. Or even military presses if you can add enough weight to make it a challenege. You can also hold your pack in front of you, and simultaneously flex your shoulders and extend your elbows for a modified shoulder press using a backpack. If you have any questions feel free to email or message me. Good luck, and happy trails