In the past 8 years of schooling, I have been required to take a foreign language. I picked Spanish, as I figured it would be most practical in the long run. Learning a language is always kind of scary, because the new language is going to be so different from your first language.
After taking 4 1/2 years of Spanish classes, I feel fairly confident with my ability to comprehend the language. I remember some things better than others, but I can say the same about history or math. Not to boast or brag, but I always got pretty good grades in Spanish. In middle school and high school, that could partially be attributed to the fact that I was one of few who actually cared; about the school, the class, the teacher, the language. But also because language learning was always so fascinating to me, making me wish my schools had offered more of a variety than just Spanish, French, and Chinese.
During high school, I would often scroll through the channels on TV and stumble upon a movie I liked, but it was only on the Spanish channel! So I would watch those movies on the Spanish channel just to see how well I could translate (if I already knew the movie well) or figure out the dialogue (if I had seen the movie before but not with enough frequency to know the lines by heart). I'm pretty sure I annoyed my family when I did this, but I thought it was pretty entertaining.
During this past semester of college Spanish, my professor would give the class a few paragraphs to write in Spanish and turn in for evaluation. Some of the prompts were vague, such as describing a famous person or a best friend, so there was a lot of leeway in it. I had remembered some words and phrases from previous years of Spanish that we had not yet learned in that class, but I wanted to use them anyway, so I did.
I got one assignment back and my professor came over to talk to me about my work. She asked how long I had been studying Spanish and I gave her the quick run-down of my previous knowledge. She then asked if I had watched any Spanish movies or shows before and it took me a while to remember that I watched English movies in Spanish in my past. It was funny that she had asked me that, though, because literally the day before that, I had started watching Velvet, a Spanish drama series that is available on Netflix. I recounted that I had done that and informed her as such, which made my "advanced" knowledge make sense to her.
Now that I am 3 seasons and 9 episodes in to Velvet, I have acquired more Spanish vocab and even some grammar, just by watching this show: hearing the Spanish and seeing the English in front of me (I watch it with English subtitles on). In the at least 10 minutes after I finish watching for the day or for the moment, my thoughts are only in Spanish.
Similarly, my roommate and I watched an entire Netflix series this past Saturday (don't judge us..) named Dark. It was entirely in German, a language she happens to be studying. Watching the show helped her remember a few German words for her upcoming exam.
Media is a powerful thing and it can be used for your benefit. I would highly recommend watching foreign media if you're trying to learn or improve a second (or third, or fourth...) language.