I didn’t read all the replies (It’s amazing the number of post / answers on this forum ^^) so this is just another one that you may or may not have already heard.
I’ve faced burnout multiple times on the past 6 months and the worst part was when I quit smoking 4 months or so ago. It was really super hard to get rid of the thing that (I thought) helped me to relieve stress.
What I’ve found out in quitting the cigaret habit made me think of my “burnout” facing. When I got cigaret hanger like super strong ones which just makes me want to jump in the car and go straight to buy a new pack… just focusing on my body, being conscious of myself, and repeating in my head “you’re worth better than that”, after just 5 minutes boom the craving is gone.
That’s only because of that, that I realised I was doing exactly the same for my japanese study but way more subtly. The moments when I needed to start studying or switch from a task to another or repeat a set of cards etc etc and all my brain was saying was just “ok why don’t we just lie down and take a nap”, “why don’t we turn on the switch and do one little run of Dead Cells”.
In those moments I was also unconsciously telling myself “you’re worth better than that” except that for studying it’s more of a shameful feeling of “so you are not capable of learning that stuff, you’re too dumb maybe you should just quit and do something easier”. The cigaret was the opposite it wasn’t shame it was something like pity for my own health.
I hope you follow me ^^
So all I want to say is yeah you are worth better than the burnout ! What you are doing IS MEANINGFUL you’re not doing a sad sad job, working for a big company or an as****le. You’re gaining meaningful knowledge. Is it hard ? Let’s be honest it isn’t hard like having a PhD in quantum physics. All we have to do is to focus and put stuff in our brain again and again and again.
We learned our mother tongue we can learn a new one !
(And don’t think kids have it easier because they are sponges or whatever, adults are in fact way better at learning a new language thank kids you can check on google very serious studies have been done on the subject !).
Now from my own perspective if you ask me, then if it’s meaningful and all, why, why this bad feeling when I need to get on my work ???!
What I think is we, as humans, are animals of rewards. That’s why we love video games, to watch movies and tv shows to take naps, to procrastinate. It gives instant small doses of quick and easy good feelings.
Learning japanese takes so much time, so much energy that after weeks / months our brain try to trigger us like : “HEY DUDE WTF ?! I’m doing this with you for the past 15 weeks and the time spent / rewards (like the first time you read a sentence in full japanese… god that feeling) has not been awesome, maybe we could do something else”
But it’s just in your brain, in your guts, the only thing you need to do is to say NO, sit down start studying again… and 5 minutes later you get back in the zone. Today you’ve learned things you go to bed knowing you did every thing you could AND THAT’S the point !
At the end of the day, the opinion you have of yourself when you spent 4/5/6/7 hours studying by opposition with the one when you spent your day binge watching a stupid tv show saying to yourself: “tomorrow I work !” …
I think you already know the difference 
What you do is Meaningful.
You’re going to speak Japanese like you speak English soon.
Never stop.
Every day matter.
Your brain is not the boss of you.
Your guts are not the boss of you.
You’re going to speak Japanese like you speak English soon.
Go to bed bed before midnight.
Wake up before 8am.
Eat well / sleep well / drink water / do some kind of physical exercise every day.
You’re going to speak Japanese like you speak English soon.
At the end of the day there is no excuse you could find that will give you a better feeling than a good day of study.
You are smart and every day of studying proves it to yourself.
You’re awesome.
You’re going to speak Japanese like you speak English soon.
Good luck 