Rucking is walking a set distance while carrying a weighted pack on your back. The name comes from the military, where soldiers do ruck marches with loaded rucksacks to prepare for carrying heavy gear over long distances, and it has since become a popular civilian workout.
A rucking workout is built around three variables: how much weight you carry, how far you go, and how long you walk. You do not need special gear to start; a sturdy backpack with wide shoulder straps and a chest or waist strap works, loaded with weight plates, dumbbells, sandbags, or weighed household items. Cleveland Clinic sports medicine physician Matthew Kampert suggests starting with about 5 pounds and working up gradually, since carrying 20 pounds for several miles is harder than it sounds.
Source: Cleveland Clinic: What Is Rucking?
Image: Soldiers on a 12-mile ruck march, U.S. Army photo by Cpl. Tae Sung Kim, public domain, via Wikimedia Commons.