> immersion only works if you're a relatively extroverted person (IMHO). Immersion turns language learning into a social activity. If you're more introverted, you won't get that social exposure

I'm a native English speaker, but I live in a country where the native language isn't English. This means I have to speak that other language every single day, not because I'm an extrovert, but because I have to if I want people to understand me.

To me, that's the incentive you're looking for.