I'm a senior developer with about a decade of experience in the .NET sphere. My advice would be to flip around your approach and evaluate if it doesn't work better that way. I would suggest that you find a project you want to make, maybe something related to another hobby or interest (even if it exists already), and start on building that. Now, for every bit that you need, you look up the theory and examples that apply to it and learn those. Then you take a break, personally I find I need at least one night's sleep, which is probably because it moves stuff from short term to long term memory. Then, you sit down and try your best to do a little something, and evaluate how that went. Maybe you executed it perfectly, great! But maybe you found you learned the wrong thing, or missed something... Also great because now you have your next step.

I would also suggest once you get a little further in your studies that you find an established project to be a part of. Both in my professional career and in my hobby work, I have found that the biggest motivation to learn something and put up with the effort that takes is by having a reason to. There are other subjects I can study for the sake of learning them, but software development is not it. I will also suggest that if you move on to actually do this for a living, that you keep a hobby project around, because programming for money is a whole different beast than programming for joy. It may sound like "extra work" but it's been instrumental in steering me away from burnout, I thought the suggestion was absolute madness, but I'm glad to admit I was wrong there!

And yeah, I absolutely hit fatigue too. Sometimes at work there are longer periods where I have very little to do, and a common piece of advice is to do self study that is relevant. Great, but after an hour my brain is full and it is like a bucket with a few tiny holes at the bottom, it needs to sit and drain before you can put more into the bucket. That is when you need to do something that isn't work. I often ask my team to go get a coffee / other drink, so we all step outside and talk about non-work stuff. Which sometimes means we cycle back to work stuff or someone hits an aha moment. I might also put on some familiar music and just zone out for a while. I also worked with someone on a hobby project once, who had in fact put a whiteboard in their shower, because they'd often find stepping into the shower meant their brain started to suddenly generate ideas. All of this is to say that non-work is as important as work-work, and why I personally very much dislike the pressures of presentism. There are concious and subconcious processes in your head and both are vital, just like your computer has foreground software running and services in the back.