As someone who's learned a few (natural) languages over the years, German remains the only one that just instills me with a sense of dread, or maybe some sort of internal animosity. Russian? Sure. French? Yeah. English? Obviously. Japanese? Still in the kanji mines but making progress. Spanish? Sweet.
But German is a blood-and-tears uphill battle for me and I just can't get over it. It's really fascinating on some level.
I am a native German and had Russian as a second foreign language. Try applying Russian Grammar rules to German, you will find they are almost identical.
Verb prefix system is the same. Noun conjugation even uses the same prepositions to decide the case. Compound words are slighly different, instead of a tram-station you would use tramlike station.
For what is worth, I find the ugro-finnic trinity (Finnish, Estonian and Hungarian) a step down towards hell, compared to German, Russian and many other languages traditionally considered hard.