Many, when they start their exercise regiment, they start with running --in my opinion, this is the worst thing you can do. Every time your foot hits the pavement you're hitting your tissue with a force that equals about 8 times your body weight, and if you don't have the muscles to protect your joints, you're in trouble.
Many believe that we humans are designed to run, particularly run long distances -- let me make a case as to why I think this is wrong.
When comparing humans to other animals, a few differences pop-out immediately: we walk upright, and we sweat. Being upright means that our ability to accelerate forward is very poor, but it also allows us to generate incredible force upwards and move forward efficiently. The sweating allows us to cool our body effectively and support our ability to move continuously -- in fact, we're so good at this, that our species has the best endurance out of the whole animal kingdom.
Now all of this seems to lend itself towards humans having good running economy, but actually, we don't -- we have a good walking economy, as running tends to favor more explosive muscles (which tire quicker) whereas walking allows our body to flow optimally. Running tends to also favor anaerobic metabolism which can cause issues long-term, walking however is completely aerobic (using fat for fuel).
Because of our bipedal nature we are also the only species that can carry. Unlike running, carrying has a very strong strength-component to it, as well as a conditioning component -- but, the peak force on your joints is far lower. What's even more interesting about carrying in comparison to lifting weights, is that you train your ability to be upright which has a massive carryover to life.
Another benefit of carrying is that it tends to favor slow twitch muscle fibers that are far more durable than their fast twitch counterpart -- this results in an ability to do more with your body without tiring.
Beyond the muscle-strengthening, carrying is also fantastic for the heart, as the added load to the body will challenge the bloodflow. And, it strengthens your breathing muscles as the ribs & diaphragm have to work harder to contract.
Lastly, there is an obvious benefit to your daily life as we often carry things like groceries, furniture, kids etc. and being able to carry heavy makes these activities less straining.
For more information on the benefits of carrying, feel free to click on the link down below
The many benefits of rucking | Peter Attia and Michael Easter - YouTube