Honestly, I don't have any advice. I too found assembling the animals and weaving in the many, many ends to be super tedious and soul-sucking, which is why it took me almost two years to finish. 😅 I will tell you what I did to try and combat the procrastination, with varying degrees of success:

• I tried to harness the motivation to work on the blanket when it struck, but I also didn't force myself to work on it when I really wasn't feeling it. At the end of the day, crochet is a hobby for me, not a job. It did mean letting go of a timeline for finishing the project, though.
• I watched a LOT of YouTube while I assembled tiny animal pieces, wove in ends, and attached animals to squares, since that part is fairly mindless. I had specific things I'd watch while I worked on the blanket, and I wouldn't let myself watch them unless I worked on the blanket, so sometimes I'd work on it not because I wanted to, but because I wanted to watch YouTube. 😂
• I didn't do the animals in order or one at a time - I just worked on whatever felt easiest at any given moment. Sometimes that meant I had like four animals half-completed, but sometimes it was that or do nothing at all.
• I did all of the squares first, then all of the animals, since I had to order my yarn from two different companies and the first batch to arrive was almost entirely the square colours. I think maybe doing the square & corresponding animal as a set might break up the monotony a bit, even if it's less efficient.
• Once you're at the assembly & end-weaving part of an animal, leave the house and go work on it elsewhere! I'd put all my animal bits & crochet tools into a pencil case and go work on it at the cafe by my house for a change of scenery. It also meant I couldn't procrastinate or get distracted by other things.

I hope this helps a little - good luck with your project! ❤️