Keeping focused on learning while several layers of abstraction deep?

So say I want to write some software involving a specific domain. Let’s say the particular domain is very math heavy, in particular calculus. The parts of calculus find in upper level undergraduate programs. Now I’ve never been particularly good at math, in part because I didn’t really care about it when I was younger.

So basic in order to even get started on this project, I have to be at least somewhat familiar with

1) The tools I want to use to write the software 2) The domain 3) The prerequisite knowledge required to understand the domain (in the case the upper level math and a few other things. 4) The prerequisite knowledge for 3 (which involves more basic calculus, algebra etc. basically the stuff I never paid much attention to in school)

My problem is I have to learn that from the bottom up. Now if I was just starting at 2 or even 3, it would be no problem. My problem is at the fourth level.

At this point, I know the resources to use, but I find it extremely difficult to even get started, as it involves grinding through hours of videos, books, etc. to reviews / learn / relearn stuff that’s so abstracted and far away from my original goal that I just can’t keep the motivation. It adds significant time cost and removes the lesrning benefit that comes with a concrete, interest and is basically a return to everything I disliked about math when I was younger.

Does anyone have any advice on how one could motivate themselves through something like this?