You and me both. As the eldest child, it was my job to walk the dog three times a day during school holidays. Most of the time I'd go alone. During those endless walks along riverbanks, through fields and down twisty country lanes I'd think and invent and create in my head. It was wonderful.
I remember dreaming up a multi-player game set in space, where every character would be played by another real person. You'd join a ship's crew and go exploring a gigantic galaxy. I was inspired, of course, by Elite on the school BBC and Star Trek; by the 9600 baud modem my Dad 'borrowed' from work and the bulletin boards it gave me access to; and by a dreamy child's desire for complete and total escape. A good fifteen years later Eve Online came out and I got my wish, just as I was settling into a busy career and saving for my first house. I've never even downloaded it.
Then there's the sketches I made in the mid '80s for a handheld computer with a touch-screen interface that would communicate, via radio, with transceivers in public buildings to give people directions and information. There was even messaging, with a kind of dead-letter-drop store-and-forward system that carried data between the transceivers on devices themselves, like a weird cross between bittorrent and the Royal Mail. I don't think I'd even heard of email at that point.
I came up with so much on those long walks. Nearly all of it has been developed in some form or other, never exactly as I imagined but always better in some ways and worse in others.
For me it's one of the most heartbreaking things about growing up: there's no time to indulge in exploration for its own sake. I can't focus my entire brain on a single thing for any length of time at all. If I could, if only I could.
I'm publicly rather derisive (in a joking way) about adults playing computer games but I know in my heart of hearts that if Eve (or indeed the new similar ones that are currently under development) is all it's cracked up to be it would be a really REALLY bad idea for me to ever try them.
As a rule, I steer clear of heroin, crack and Elite-type MMORPGs... ;)