Shere and utter boredom. I used to LOATH Pokemon, like seriously hate it, because I watched Digimon first which I loved, when I saw Pokemon I was like "What?! These things can't even talk! How the hell are you meant to understand what they are saying *twitch*
Then I got a GBA, played Incredibles and that Shark Tale, needed more games. At games day in school, I played a friends Leaf Green but hated it, didn;t give it the time of day. Then I got desperate for a game to play and couldn't buy one like that so I asked a friend for a game, all they had was Sapphire, I gave it a go and BAM! I fell in love with the whole RPG Simulation concept of it :D
Also, I deleted a friends Emerald Account with Rare Pokemon like Mew and all that, I'll never forgive my myself for it, but he did in an instant :o