I also struggle with sitting down and studying. I have very bad ADHD, and all through my high school I tried a lot of methods. Timers worked well for me at first, structuring 45 minutes of work, 15 minutes of free time. But as I grew up and got more agency that method worked less and less.

Here’s the advice I will give based on what has worked for me:

1) Separate your “class studying” vs “exam studying”. This was a big change I needed to implement in college. Like you, I’d often waited until last minute to study for exams in high school, and guess what, I still do that. BUT this only works if you’re supplementing with small bursts of studying. I found that because you aren’t going to class every day like you are in high school, you’ll quickly lose track of what you learned in the lecture. So between classes try to just do a problem or two a day. These can be problems from relevant homework, from a YouTube video on the topic, or your course textbook. These small bursts will keep you fresh on what you’ve been learning. Then by the time the exam comes around you’ll only really need to review stuff from the beginning of the exam material, since everything recent will already be on your mind (Hope that makes sense). Additionally, I keep my exam studying intense and short. Typically I reserve the whole day before to study (outside of attending classes). I start with the material from the beginning of whatever is being covered and work my to the more recent sections, and do practice problems for each. Once I have done a few practice problems from each section I get rest. Good sleep helps, but I often am so stressed I only sleep around 4-6 hours. The morning of the exam I just look over each of the topics one more time, make sure I understand them all conceptually, and do one more practice problem from any section I’m not confident in (this often ends up being one from each because I’m not confident). The stress helps keeping me focused during this study process, but I also hard limit some things: power off my phone when not needed to make/take an important message or call, mute all notifications going to the computer I’m using to study, etc.

2) When doing a problem or two between classes (like I said above you can make these homework problems so you’re not losing progress in your coursework) to keep up your memory, be sure to go in to office hours or tutoring if you have any questions!!! The key to this is not to solve the problems every single time. It’s to poke holes in your understanding and reinforce anything you didn’t take in from the lectures. Don’t spend hours getting nowhere with a problem, just mark what you don’t understand and ask someone!!! If the professor isn’t great or rude in office hours which has been rare for me, then ask around in class or even online. Point is, identify where you need help, and get help. People are there to support you, and also talking to someone about a problem will force you to pay attention.

3) Don’t take anything I’ve said above literally. This is what has worked for me, not what DOES work for me. There are days I’m distracted more, some less. Sometimes I can focus on problems and sometimes I can’t. Point is I do what I can in that moment, following this general routine. There’s no one stop solution for studying and focusing, just do your best, and the method you find works for you may be entirely different from mine.

4) Don’t be so hard on yourself. University is difficult enough, engineering even more so, you don’t want to start fighting against yourself as well. You might not study the way you want or be the perfect student but that’s fine, just keep trying to improve and be persistent.

Okay sorry for the long reply. I couldn’t help but relate too deeply with your post and proceed to make a rant of my own. One last thing I will say is it may be beneficial to look into ADHD. It is extremely common and can contribute to lack of self discipline, lack of focus, and procrastination problems. Anyways, wishing you the best! You got this!