Farmer's Carry

Pick up a weight in each hand and stand tall, shoulders pulled back and down rather than hunched up around your ears. Walk with even, controlled steps, letting the weights hang at your sides instead of swinging them for momentum. Your grip will want to give out before your back or legs do, so if your hands are opening up, that's the limiting factor here, not fatigue anywhere else. Keep your ribs stacked over your hips rather than leaning back to counterbalance the load, and take normal-length strides rather than shuffling to keep the weights still.