How to keep healthy?One important thing is to exercise often.The Smith families try to exercise every day.Qiang Smith can not exercise in the morning because he must be at his job at seven o'clock.But he runs every evening.He walks a lot,too.He walks to school every day and after school he plays basketball with his friends.Qiang goes to a yoga class three times a week,but it isn't always in this hard way.Last year Mr.And Mrs.Smith drove everywhere.They thought they should use the car all the time.Now the Smiths walk more,and they all feel better now.And they think they mustn't be too hard.They don't have to exercise every day,but they sgould try to keep in good health.