The task involving rucking is simple. You're only required to walk for miles carrying a weighted backpack.

The term "rucking" is from "rucksack," a carrying device developed in the mid-19th century, which the military refers to as their "backpack."  Filled with gears and necessities and weighing almost 200 pounds, soldiers carry these around while walking 25 miles and more, according to Men's Health.

Rucking has built, toned and strengthened bodies of the NAVY Seal, but the activity can also work for the average person.

"It's simple, and it delivers a lot of health and fitness benefits," said Doug Kechijian, Doctor of Physical Therapy at Peak Performance in New York. Kechijian is also a former soldier in the U.S. Special Forces.  

Doing a 30-minute walk with a rucksack can burn up to 325 calories, three times more than an regular morning walk. The activity also helps relieve and prevent back pain, as the weighted backpack can strengthen the back muscles. This is particularly helpful for gym buffs who have developed a disc bulge.

There are also cardio benefits to rucking, one of which is not found in other cardio activities like jogging, which can sometimes lead to injuries. Dan John, a prominent strength coach from Salt Lake City, Utah, said that aside from weight loss, the activity is the "holy grail of work capacity," one that can "build the foundation for all other physical activities" that makes every other physical activities easier to do.

GoRuck.com describes this workout as a social fitness activity that can be done among friends, family and even with dogs. Rucking is also less expensive, requiring no memberships at the gym, nor special equipment to use and programs to follow. In fact, GoRuck's recommendation includes a simple kid's diaper bag or a case of beer for the workout.

Finally, rucking affords the person the chance to enjoy the outdoors, which helps with brain function. "Rucking outside, having to read terrain and adapt, works your brain in a totally different way, and that can provide positive changes in your brain," Kechijian said.