Thank you, Brian!
I'm from Belarus so I know Belarusian and Russian languages at the native level. Then I started learning English at school, so now I'm quite fluent in the language (still grammar, tenses and speaking overall are tough part; lack of practice you know). I think about getting higher education abroad (EU, probably) so I consider learning German or Polish (the last one is actually easy for me as my mother knows it).
The content is very helpful as it gives some interesting exercises that involve physical memory. I like your realistic thoughts about time needed to become fluent in new language.
P.S. I do also agree that apps like Duolingo are not worth your time.