Ja, ich kann. 
When first learning, I also tried out all sorts of things like audiobooks, textbooks and apps, took lots of language school lessons. Found lots of those quite useful for getting the fundamentals, but I just didn’t seem to be able to get past a certain level learning the normal way like that.
For me, it was much much more so in just making it a part of my every day life. Podcasts about topics I was genuinely interested in, original German tv series that I actually wanted to watch, so it didn’t feel like ‘homework’. (One of my favourite shows of all time, the Norwegian series Skam, got a German remake, highly highly recommend that for anyone wanting more exposure to how German is actually used by The Youth today!)
Also, somewhat helpfully, my fiancée is German, so we started off doing one day a week speaking only German. Used to play lots of language driven games on those days (really recommend Rory’s Story Cubes, a great way to get you using vocabulary and putting yourself in unusual situations that wouldn’t normally come up). That was when the real major breakthroughs came and I really noticed a huge improvement, and more than anything, a confidence.
I still don’t really know anyone here (also a Berliner) who’s learned the language and would actually call themselves fluent or not have huge confidence wobbles from time to time.
Applying for German citizenship just now - Daumen well and truly gedrückt!