My 13 yo son doesn't do sports or have any 'activities' outside of playing games online with his friends and walking to and from school daily (25 minutes each way). I feel like that with what he is getting at school is enough in the colder months. When it's warmer we spend an hour outside after school in the yard, biking, with friends. Outside of online play, he reads a lot and is getting good grades. The same for his sister, 10.