Just do it.
Do it with a purpose
Having a solid intent behind reading a paper or fully understanding its content absolutely helps motivate your reading. Also, it provides the proper lens to reading that paper. If you need to understand the intricate details then it will take more time, but you know you only need to read to understand the core part, not any fluff language that isn't giving you the relevant info.
If ya just need to understand the gist then ya don't need to read as deep. Always can start here and reread if ya need more depth. Same applies to needing only certain sections of the text.
Do it a bit at a time
Tricking yourself into doing it for longer by doing it for 2 or 5 minutes and when your brain thinks or wants to do something else, treat yourself to that something else after 2 or 5 minutes more. Repeat until you're not making progress.
Of course this enters the lengthy discussion of optimizing how to focus and do tasks. Could try mindfulness meditation, or yoga. Tons of things to try to figure out what works best for you.
Also, if you find you need to read something else to better understand the current work, then prioritize that prior knowledge first. Same can go for practicing skills or really understanding key concepts.
Do it with accountability
Hold yourself accountable by working on it for some set amount of time a day or week. Tracking the time you commit to an activity can be useful when to encourage you to do more if you only did a bit. Or reading it for some time before throwing on a video or playing or worse, social media scrolling. High dopamine activities will make ya want more of them so do em later in day and do the reading earlier in the day. Sleep will reset your brain.
Do it with a friend
Share your suffering. :] This is accountability + a friend to talk the content and concepts over with. You could take a rubber duck approach where they didn't read it but will listen and ask thoughtful questions if being more responsive than an actual rubber duck. If your friend or colleague also read it then discussing can help you both understand it.
Similarly, can read as if you were learning to teach someone else the concept. Works great esp. When targeting non experts.
Do it with more of your senses
Definitely taste the book. Don't forget to do that. I consume a book for breakfast daily.
When in undergrad or grad classes and I was studying, I would read aloud to slow down and fully comprehend the text, Sometimes along with writing out the key points in note form. Same goes for attempting to make visuals or trying out the thing I was learning with hands on experience. Basically do all the learning styles. 😆
Personal Experience
I have had multiple papers and books be daunting to me, esp. throughout the literature review for my ongoing paper. These have covered a wide range of intertwining fields, including, probabilistic and algorithmic statistics, math, machine learning theory, & computability theory. In this case the problem and breadth was daunting. That's okay because I wanted to learn this and do this.
After all that I found papers to be "daunting" as in "I don't want to decipher the jargon to understand the intricacies from this niche field that is incredibly new and not as well formalized as the rest" (looking at you, algorithmic statistics). This is an important difference from feeling that I couldn't understand the text. I had the latter feeling more in studying during undergrad and early graduate school. The more you learn, the more you find overlapping patterns you can leverage and also realize the more others don't know and that's alright because you wouldn't want to force people to have to do all that reading you had to do.
Though you certainly come to appreciate writers who respect your time. Btw, philosophy doesn't tend to be those kind of writers, in my experience. Physicists, now they get to the point.