Fitness is neither one thing nor a combination of things. Fitness is activity-specific. For example, fitness to run the 100m is different from fitness to run the 10,000m, and fitness to run any distances is different from fitness to swim any distance. The term 'fitness' is only meaningful in the context of a specific activity. Running does one thing and one thing only: it makes you fit to run for long periods without getting tired, which is a very specific ability that has little or no value to most people. High-intensity strength training, in contrast, improves the condition of the muscles and bones, which carries over to every other task that one encounters in life, improving one's ability to do everything from scale a flight of stairs to play recreational sports. Running for fitness is an archaic idea that is rapidly being discredited as the world shifts to the more progressive notion of training with sort-duration, high-intensity training protocols. People with an emotional attachment to running will never get it, but there is hope for the rest of the world.