First off, before I start I’d like to express that I love learning Japanese and I most definitely want to be proficient in Japanese. However I seem to have this undying lust for other languages, most especially Mandarin. It is incredibly tempting to split the time I have each day to learn Japanese in half in order to also learn Mandarin. I am unsure of what to do. So I have pondered this quandary for a bit. Perhaps to keep my lust for Mandarin at bay I could dedicate a small amount of time each day to actively work on it; but I would continue doing the exact same amount of effort and time into learning Japanese. This is how I envision such a thing would work. Let’s say everyday I commit to actively learn Japanese for 3 hours each day, I would continue to do that but I would add in an extra 40 minutes of active Mandarin learning each day in addition to the 3 hours of Japanese. As for the passive learning part I would continue listening to Japanese for 10 hours a day and add in just 2 hours of Mandarin listening a day. Now this might indeed be a bad idea but I’m considering trying it out. If I were able to retain this kind of schedule then I would likely still reach language proficiency in Japanese at the same time as I would have before, say in 2 years time. Now one might ask ‘why not focus that much more on learning Japanese instead?’ Well that’s a good question, however I thought about that and have concluded that for me I have found that going over what I usually do for Japanese; I in a way get sick of learning Japanese but I often still have energy to do more language learning but just not of the Japanese variety. So taking that into consideration perhaps I could take on Mandarin at the same time without reducing my Japanese learning. One concern I have though is being able to include the extra listening, for I for the most part am already listening to Japanese whenever I can, which is about 8-10 hours each day. I think in this area I would struggle the most to add 2 additional hours of foreign language listening. Perhaps I would have to compromise here and listen to 2 hours less of Japanese so that I could fit in the Mandarin listening. And if I did that, Would I still learn Japanese at the same rate or would my progress slow down by a fraction? And if it does indeed cause my Japanese progress to slow down by a bit how much would that be by 20%? 10%? Perhaps 5%? There’s no way of really knowing. How much of a decrease in Japanese acquiring speed am I even okay with? I would say 5% would be an acceptable amount of decrease as that would only mean a couple of months slower if I am to assume it’ll take me 2 years to learn Japanese. Also another question remains, how much benefit would I reap if I spent that small amount of time each day to learn Mandarin? Well let’s do the math 40 minutes a day for 2 years would equal about 487 hours of Mandarin learning. If such a different language from English such as Mandarin takes 2200 hours to learn then after 2 years of learning Japanese, and Mandarin on the side, I would still have 1713 hours left of Mandarin learning(Hypothetically). This would mean that I would have just under a year and a half of Mandarin learning to do to hypothetically learn the language. So to sum it all up to learn Japanese and Mandarin to decent proficiency it would take 3 and half years rather than 4 years if I learned them separately with the added bonus of keeping language lust at bay. Of course this is all hypothetical speculation and real world results usually differ quite a bit so all I have left is to put it to the test, maybe test the waters a little at first and if it seems to be working fine then I will go ahead and do it. And after 3 and a half years I guess I’ll know if it worked.