How much exercise is enough for good health?

Hi, I think that three times a week of aerobic is perfect for your health and looks. I remember when I trained aerobic three times a week, I never felt better in my life. I lost all the fat on my body and I had much more energy than before. However, it would be even better to train 4-5 times a week, but few people have that much time. Exercises are more important that many people realize, because they prevent many diseases and keep you fit. If you don’t have time to train something or to go to the gym, you should exercise at home half an hour a day. I think that it’s terrible that so many people suffer from obesity, especially children. How do their parents let this happen? I don’t remember the last time when I bought my son a coke or a hot-dog. I always cook him something healthy with vegetables and high in fiber. He also goes swimming three times a week, and his health is perfect.