The reason you can’t run for long distances. Has very little to do with your cardio and leg endurance. The truth probably is your feet.
Your feet aren’t properly conditioned to go for distance. Cuz your shoes aren’t right for your feet.
You’re probably thinking

“I have the best running shoes on the market. What are you talking about?”

You might have the best shoes on the market. But the truth is that shoes aren’t good for running.

Ancient man was able to track animals for up to 20-40 miles before closing in for a kill. How do you think the primitive man was able to accomplish this?
It wasn’t because of Nike free runners.

It’s because they were barefoot or had flat sandals. You might be curious as to how being barefoot or wearing limited shoes is helpful for running.

The secret lies in the structure and anatomy of the foot. The homo sapien foot is designed to be wide and flat-footed. This shape allows for the force of your body to be displaced across a larger surface area which reduces the strain on the legs, hips, and back. The more force dispersed by your foot, the less of recoil on your body. Which enables you to run longer using less energy.

The modern shoe limits the ability of your feet to release energy which ends up working against your body for every step you take.
Think of it like driving a car with an emergency break on.

The more you press on the gas. The more damage your doing to your body.

I recently purchased a pair of Trail Running Sandals.

https://shammasandals.com/collections/all-products/products/super-browns

It has been a life-changing experience. I’m able to run longer without getting tired and without any strain on my body.
At 200lbs long distance running has been a challenge for me. But since acquiring the sandals I can rack up miles at was seems like a Gods pace and it feels as if I have an infinite gas tank.

I highly recommend people look into minimalistic shoes for daily footwear.
Your back, hips, and legs will thank you later.