Earlier quoted context omitted.
As far as language goes, my advice for learning a new one would be the exact opposite of what you say. Force yourself to use the language all the time, everywhere. Otherwise people will just default to English with you, and you'll have a hard time learning the local language. It'll be very stressful for a few months, but, in my experience, will get you conversing in about half a year.
As someone who has lived in this environment for this long, it doesn't work that way. This is not a language that shares any traits with English. It is hard to get going, and the vocabulary takes a considerable amount of time. You can't switch to Finnish at work, as you simply would not be able to get by, and you can't do it at home as it changes the dynamics of your relationship. This is not an excuse, it's reality.
Finish kids don’t need ten years to learn the language either, do they?