A good rule of thumb is to not carry more than ⅓ of your bodyweight. In 1950, Colonel S.L.A. Marshall published a book called The Soldier’s Load and the Mobility of a Nation, which is still widely regarded as the reference of choice on the matter. In this book, Marshall details at great length how and why soldiers are required to carry too much weight, which was as relevant then as it is to today’s combat loads in excess of 100 lbs. Marshall contends that based on past studies on the loads carried by armies throughout history, the soldier should be limited to ⅓ of his bodyweight. In our experience, we've found the ⅓ rule to be true, and a great goal to work up to over time, and not exceed. Remember, if you need a bigger challenge you can always increase speed and distance rucked, too. If you do need to go above ⅓ of your bodyweight, such as for military training or backcountry hunting, make sure you’re ready for it and that you progress safely.