There is a saying in my culture, which says something like ”How many languages you know, so many times you are a human being”, implying great benefits from learning new languages. I may be controversial here (and your foreign language teachers and/or parents may not agree), but I believe that there may be a better use of your time than learning foreign languages other than English.
I have spent most of my elementary school, high school, and university studying two foreign languages – English and German. In English, I spent countless hours getting to a proficiency level that allows me to operate more or less at a native level (putting accent aside). But the investment was worth it, as I reaped the benefits. I did my university education in English, and used English throughout my entire career. Luckily, English is the language that most people around the world learn as the first foreign language (or it is their native language in the first place).
The problem was with my learning of German. I estimate I spent around 2,500-3,000 hours studying German between the ages of 10 and 21. That’s roughly a year (310-375 days to be precise) of 8-hour days! I never quite got to a proficiency level though, due to a combination of the quality of education I received as well as my interest in the language (as opposed to English). And the benefits? 1-week holiday in Germany, where I could use my German skills. Hopefully some improvement in my brain grey matter due to the ‘brain exercise’ of learning a foreign language (the benefit of that declines after the first foreign language though). But otherwise, no significant use in my career, education, or personal life.
People believe that learning a foreign language will help you in your career as you can communicate in the foreign language. Depending on the job, it certainly helps to know the basics to be able to strike a conversation (e.g. in the hospitality industry) – but for this level, you may be able to do with a fraction of the hours I describe. For any professional positions, e.g. in business or finance, it is only fluent/native level that counts. For example in London, if a position requires German language, they will hire a German/Austrian/Swiss person, rather than go with my semi-baked language skills. It will never be my strength.
I do not advocate dropping the language study completely, but to think about the time investment you are making and the opportunity cost of the time. When I was at McKinsey and was spending a few months on projects in Russia, I spent some time learning Russian alphabet and basic vocabulary so I can get by (as many people there do not speak English) and also show some appreciation to the people/culture I was operating in. I think I invested just enough to get the benefit I wanted, without spending too much time on language I may not need again (and likely will forget most of it as soon as I stop using it).
So now you may ask what to do with the extra 2,500-3,000 hours that you may be able to free up? If I could go back (and the school system allowed it), I would probably divide the time between investing more in English to get to my current level earlier, do more sports (for health-reasons as well as enjoyment), and invest in other areas, in particular IT/programming skills. It does not matter much what you want to spend the time on; the point is to think not only about the marginal benefit of doing something, but also about the opportunity cost of doing it – where do you get the most return (from education, career, or a happiness perspective) on the time invested?