I started learning English at 6, but it wasn't mandatory at schools until 10 or so, going to about 17. They start earlier now, but most people here in Spain still manage to go through 10 years of mandatory English education without actually learning anything.
I didn't learn much at school. Satellite TV ,computer magazines and finally the Internet did it for me. 90% of what I read is in English now, I buy my games from the UK to get the English version instead of a poorly translated and more expensive Spanish version and tend to watch movies and TV shows or read novels in English, to avoid missing all the funny jokes and wordplay.
It's sometimes a bit silly because, for example I might give someone a book or a link to some website, and he will look at me funny and say "Man that's in English"... I just don't notice or really think about it anymore
I have a horrid accent though, because I dont' get to actually speak a lot.