Why physical activity is important for you?

I saw an article in Internet about a guide to Healthy Active Living. A part of this article is the relationship between modern lifestyle and physical inactivity. I give you a summary of what says the article.
Nowadays our lives are very different compared with our grandparents. The didn't use to need do so much exercise as today, because most of them did hard physical work all day. There were fewer machines and everything had to be done by hand.
Today many more young people can study. This means that the students have to spend many hours sitting at the desk. They start working later and their jobs are sedentary.
Due to this, those who want to keep fit have to find some time to do exercise. This means taking up some kind of sport like football, swimming or tennis. Most moderns towns offer sports facilities in the form of leisure centers where you can find covered pods, tennis courts or gyms. Usually, they are not expensive because they're subsidized by the town hall.
Therefore most people can afford to practice some type of sport. Apart from this, there's usually a café or a restaurant where young people can enjoy some kind of social life.
To conclude, our grandparents would never have imagined that it wouds be necessary to go to special places to sweat.