I get winded walking to the refrigerator! lol Long distance running requires endurance and is a form of continuous running over at least 5 miles. Do you enjoy running?
Running is definitely not my thing.  I do like walking though - put my music on and just lose myself for a bit.
It is a tough sport! Physiologically it is mostly aerobic in nature and you need stamina as well as a lot of mental toughness. 
And good knees!  I know a few runners and they always seem to have issues with their knees due to it being high impact.
I would think the knees would definitely suffer but it's definitely good for the heart as it is used as a means to improve cardiovascular health.
Yes, I hear a lot of runners have a very low resting heart rate as well.
Absolutely! Running improves fitness levels and increases the activity of enzymes and hormones that stimulate the muscles and the heart to work in a more efficient manner. 
I did not realize it increased hormones and enzymes!  What other benefits are there?
Well, the military use it as a component of their military training and have done so historically.
I think they jog with all their gear on during times like boot camp don't they?