Some days I get in some exercise on other days I go out and play. I think that if you enjoy an activity you are more likely going to get better exercise than if you are just doing it for the sake of exercising. Tossing around a Frisbee can be an aerobic activity, but nobody does it just as exercise. A day of skiing is a day of playing in the snow, it isn't a day of working the quads. Why do we focus on going to the gym and hitting the stationary bikes when we own real ones? Do you think of your exercise routine as a form of work or play? Would you do more if you had a different mindset?
For me I consider playing or sports my form of exercise. I guess there are just people who doesn't like sports at all so they prefer working out in gyms. I think what's important is staying healthy and fit. I do agree with you that other people should also consider trying out sports and have fun while doing it.
I'm getting old so I can't walk into a gym and pump iron . . . or whatever. To pass time I always play table tennis with some other old buddies. It not only helps me stay fit but I don't have to pay any fees I would be charged to have some personal trainer tell me stuff I already know.
For me, playing sports is always the better option. You play with friends, it's competitive and there is a more obvious goal to achieve. As in, you HAVE to win, at least that's how I feel when playing sports. Running on a treadmill for an hour is never going to be as fun playing a sport. Still there are advantages to working out in a gym. The biggest being that there is less chance of injury. One tackle in football and you can be out for weeks, which is obviously going to affect your fitness levels and progress you've already achieved. Still, I'd rather have that risk and have some good old competitive fun!
I joined the gym but never go. I also have exercise machines I never use. I think the reason people go to the gym instead of exercising at home is because they see other people and it gets them out of the house. I like riding my bike for exercise, but my favorite way of exercising is walking my grand-baby in his stroller.