I struggled with this a lot when I was in school.
First off, I found this post really helpful back in the day and it really changed my perspective on things:
https://www.smogon.com/forums/threads/ama-ray-jay.3495990/#post-5137794
Basically, the idea here is you must find a way to make whatever work you are doing have intrinsic value for you. If you really just don't care, no amount of rationalization or planning is going to make you want to do it. So you must find a way to make your work matter to you, perhaps by getting involved with your fellow students if it's school, or your coworkers if work. That helps raise accountability and positive peer pressure as well.
This ended up being the case for me. In high school, I really did not care about my work at all, and my mom had to nag me all day to get it done. Barely finished in time to graduate. In college and graduate school, I found myself a lot more self-motivated and excited about what I was doing and I ended up being able to make time for things and get it all done while on my own.
In terms of more logistical tips, this year I've started off every day making a to-do list of whatever I wanted to get done that day. Break down larger projects into smaller chunks. If it's an essay, it could be something like "write 2 pages today". Organization and sticking to a schedule, perhaps unintuitively, ends up freeing you up. And writing things down in general is more helpful for goal-achieving as it keeps your mind productively focused on specific tasks to
do rather than ambiguous anxieties to just worry about.