Advice on completing assignments

I'm in college, and I'm taking a summer writing class that has a lot of dense reading. I've been procrastinating like crazy, to the point where I haven't even completed a single assignment. I've missed multiple classes, telling myself that I would do work during class time, but I haven't. Every time I try to sit down to read or complete the worksheets, its like there's a wall just completely stopping me. It's stressing me out like crazy. This has been a pattern for me taking these classes and I'd really like to break it. However, the more I think about it the worse I feel about it and the more it piles up.

It's not like I'm bored or disinterested; I actually really like the material, which makes it more frustrating that I can't seem to get the work done.

A lot of the time I hear "just sit down and do one thing at a time" but idk, that doesn't usually work for me. Any other ideas or tips?