Running up and down a field for 120 minutes....that isn't as hard as people make it out to be. I referee high school and college lacrosse games and that sport is constant up and down sprints with very little jogging at all. I have no cartilage in my knees from playing college football back when turf was crap indoor/outdoor carpet so I pay for it the next couple of days between games but its worth it.
As for a real sport it comes down to TWO games on the planet that incorporate everything...American Football and Lacrosse. Speed, power, agility, explosive power, MENTAL toughness, field awareness, etc...I could go on and on but girls or boys kick ball is just that...KICK BALL!