Fitness motivational videos?

This is a rant post, so if you are not in the mood for rants do not continue reading.
I really can't understand the big success of motivational videos and of the whole motivational approach to fitness.
I mean, doctors and dietologists say it all the time: every human being has to move her/his body to stay healthy, and the calories intake should never exceed the daily need of energy. Obviously the more you move your body, the more you need calories. It's just plain maths.
If you eat too much and do not move your body enough, you'll become fat, and being fat leads to a poor life quality and diseases.
So if you want to stay healthy you should move your body (it does not need to be "sports", just making your heart pump is enough) and avoid an excessive calories intake.
Otherwise, you'll loose your health.
Sounds simple, doesn't it?
So now, why do people need to be motivated to move? Preserving health and a full functional body isn't enough motivational?
Do you really need a video with bombastic movie quotes?
Do you really need a television star telling you to go out for a walk?
Don't get me wrong, there are some motivational videos on youtube that are very good, this one for example is great:
But actually, why people need to be pushed to stay healthy?
For every living creature survival is the absolute priority, and when you know that moving your body equals to survive (or to live longer or better) you shouldn't need more.
Maybe the reason is that most people consider exercise like a punishment.
Well, there are many levels of training. Top athletes (or people that just want to always improve their performance for the sake of it like myself and lots more) train hard many times a week.
But if you want just to stay healthy you don't need that, just go out for a long walk with your dog, go to the court to play basketball or to the park for some frisbee or badminton, use a bike to commute... there are so many enjoyable things you can do to stay healthy.
Do you really need a Rocky-Balboa-style speech for it?