1. I do think that they exercise around the clock because if you don't go to the gym every two days or at least every week, you will not be able to hold a heavy barbell for a long time as the people in the picture do.
2. Fitness is not the only way to keep fit. You should also eat healthy food and get enough sleep. But still it gives priceless support in a healthy lifestyle.
3. I had to do sports after catching a cold. In my opinion, exercising is the most useful way to get back in shape and repair your own health after lying in bed for a week or two. It was also a fantastic experience.