When it comes to exercise, kids tend to imitate their friends. Vanderbilt University researchers found the largest influence on how much moderate-to-vigorous physical activity 5-12 year olds in after-school programs got was how much their close friends got. The kids in this ethnically diverse group also altered their activity level by 10% or more to match their friends.
PositiveTip: Encouraging your child to choose friends who are active can promote their health. This might work for the whole family, also!