Why are kids so lazy now?

Ok. I am a teenager and i noticed that a lot of kids (older and younger) are lazy s. Im sorry but lots of people are not active and don't play any sports and are overweight (no offense so overweight people) but it has increased greatly. Im not saying im perfect but some kids don't even like gym. Kids are supposed to love gym. Like in my gym cl almost all the girls did better than half the boys in the situps and pushups for fitness testing. (im not ist but the boys should be able to do more our health book even said) what is happening to this world? Why is athletics decreasing?