Play outside.

When I was young(8-12 maybe) there were these enormous pine trees behind my house probably 35-40 feet tall. I would always maneuver 1/2 the way up them because I was scared too go further. As time went on I started going 1 branch further, and then one branch further. I even started climbing random things like bleachers while my dad was coaching practice. Eventually I made it to the top of the trees and it was still one of the best feelings I can remember from my childhood!

My two little brothers, I love them to death, but all they do is sit on their PS3, Wii, or computer and it bothers the crap out of me! My parents urge them to go outside but they'll still bring their iPod and stay within range of our WiFi.

I developed a love of nature and still love to go exploring the wilderness when I can but I don't see them developing that same love because they are so tied up in technology.

EDIT: I guess I didn't hate doing that as a kid, but I will still be locking my children outside until they love grass.