The best way to learn anything is by creating a habit and sticking to it. But this can have its downsides when you start to experience burnout. When you experience burnout you need to not be afraid of switching your habits and creating new ones to continue your journey. Burnout can come from simply boredom. Or it can be due to your study method having less of an impact and therefore it's a sign you need to change your method. So if your habit was to study Chinese for an hour a day and within that hour you do flashcards, even though you are studying for an hour a day you might be doing less cards or simply studying less efficiently. The best way to guarantee efficiency is by guaranteeing that you're enjoying yourself. You don't need to figure out (although it's sometimes good to) why you're experiencing burnout, but the best thing to do is to keep things interesting, which will help you feel like you're progressing.

For me when I started learning Chinese last year I really loved flashcards. Not because they were innately interesting, but because they're an insanely good way to improving your vocabulary quickly. With the fundamentals that was fine, but because I have advanced to an intermediate level of Chinese, an extra 20 words in a day is a drop in the ocean to when I only knew 200 words. Back then it had a massive impact on the level I could understand. I felt this burnout after a month, but continued flashcards for another 9 months until I finally stopped when I started my trip.

For me flash cards are a great tool for quickly improving vocabulary, especially for say a test. But it's easy to get bored of so unlike before when I swore by them, I now feel they are just one of my tools in my arsenal to my goal of fluent mandarin. And this is important identify that a way that worked before isn't always a way that will work forever.

The more tools you have to achieve your goal, the more variety you have when studying. If your only tool to learn something is just to take a course in it. Then you are setting yourself up for failure, boredom or both. To achieve a long term goal you need lots of different methods and you need to find the method that suits you best. And that suitable method may change dependent on your environment, situation or ability in that skill.

For mandarin I have the following main methods:

Flash cards, Watching tv shows, Listening to podcasts, Reading books, Textbooks, Speaking to natives, Typing to natives

And I don't do them all at the same time, otherwise I'd be spreading my time out too thinly. None of them are 'better' than the others, and they all have their pros and cons. You need to find a balance, and when you get bored or your situation changes you must remember switch things up. Right now I'm concentrating on podcasts and tv shows, which are improving my passive vocabulary and and I'm speaking to natives everyday since I'm Taiwan to practise some of that passive vocabulary.

Don't be afraid to change your habits. Don't be afraid to build new habits. Because you not wanting to continue your habit might not you being lazy. It might be because your situations warrants so don't ignore those signs. Embrace them and act before it's too late. But remember you can't break a habit before your make a habit.