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?
heart to work more efficiently. Endurance running is often a component of physical military training and has been so historically. Professional running is most commonly found in the field of sports, although in pre-industrial times foot messengers would run to deliver information to distant locations. Long-distance running as a form of tradition or ceremony is known among the Hopi and Tarahumara people, among others. Distance running can also serve as a bonding exercise for family, friends, colleagues, and has even been associated with nation-building.
Long-distance running
Long-distance running, or endurance running, is a form of continuous running over distances of at least 3 kilometres (1.8 miles). Physiologically, it is largely aerobic in nature and requires stamina as well as mental strength.
Among mammals, humans are well adapted for running significant distances, and particularly so among primates. The endurance running hypothesis suggests that running endurance in the genus "Homo" arose because travelling over large areas improved scavenging opportunities and allowed persistence hunting. The capacity for