How do you know when you've met "THE ONE"

[winneythepooh7]

I hear people say this all the time too......for someone who is 110% single, I know I've definately not met "THE ONE" yet, but for those of you who have, how did you know when you met "THE ONE". You hear people say all the time "I knew when I first laid eyes on him that he was the one" but I don't know if I buy that.