Both good points above.
Also, evaluate the beta reader feedback. They gave you a bunch of feedback, but the percentage that will ultimately be useful to you is almost certainly less than 100% of whatever the person said.
The useful percentage of feedback in the beta comments is probably somewhere between 10% and 90%, depending on the reader. As the author, you are entitled to decide if they are wrong on some individual point. In fact, I'd argue it's your responsibility to evaluate the feedback. You can toss some aside, if it is wrong-headed.
If you haven't done so already, skim ahead on the feedback you have. I had one beta reader (of sixteen) who began verbally abusing me at the one-third point. This person began yelling at me in track changes. Needless to say I did not incorporate much of that person's feedback.
Second. With some beta readers, some of the feedback I got was right on, and easy to fix, and some more was right on, and more foundationally problematic to fix. By doing the easy stuff first (which required perusing all their feedback) I could get through a good deal of the comments, which put a little wind in my sails to tackle the harder parts.
Last thing. When you have finished this or any editorial round, the knowledge that your draft is markedly improved works wonders to rally for the next lap. Keep in mind that you are running a marathon, and right now don't feel like finishing the lap. But when you do finish it, be that sooner or later, compare the quality of the result to what you started with. The improvement will buoy your spirits for whatever must happen next.
