The Scientist,
The world's greatest athlete is decathlete Ashton Eaton. Ask Usain Bolt. I referenced Rafer Johnson earlier which you have ignored. And, once more, I am talking about "running" not "jogging". The super heavyweights cannot run so walking and sprinting is all they can do but those of us who look more like Pavel and Mark Toomey than Dan John and Mikhail Koklyaev can and should run. One does not need to run marathons or even half marathons but if one weighs under 100kg and cannot run a 10k all out I would suggest that they are lacking in something. Running has other benefits besides the physical. I am outside with the mountain bikers, kayakers, birders, photographers, etc. as well as the hawks, vultures, owls, geese, coyotes, rabbits, deer and so on. And we are all, fish/fowl/human, having a better time than the guy in his garage pressing his kettlebell. I am also that guy in his garage so I know what I am talking about.
Brian D,
The easiest way to improve at distance running is to run negative splits. Try to be faster in the second half of the run. The faster you run the first half the harder it will be to beat your time or distance in the second half. I run 1-2 hours on horse trails along the American River in Sacramento, CA then turn around and try to beat my time on the way back. This is both mentally and physically challenging but the results speak for themselves. I have focused on negative splits for the last 12-15 months and am now faster at 46 (one month shy of 47) than I was at 30. At 5' 9.5" I am under 180 for the first time in 15 years. I use barbell, kbs and body weight exercises and prefer the GTG method for strength but 2-3x a year I will do a 4-8 week cycle of barbell deadlifts (traditional, sumo, one-legged and suitcase) or the ROP.