I've heard that you burn more calories when you are outside playing because you are more engrossed in your changing surroundings. Your eyes and ears and other senses are getting more stimulation, so you don't notice that you are riding father, running faster, swinging higher!
And when you're outside, you can stop for ice cream and not feel guilty!
They're up in your face, they don't think you belong
Man, you got it, you got it goin' on
What breaks the weak just makes you strong
You got game, baby bring it on, bring it on