I went back to school in my late 20s for this. Ultimately what everyone says is true, you learn the stuff by doing problems and at the end of the day lectures

I went back to school in my late 20s for this. Ultimately what everyone says is true, you learn the stuff by doing problems and at the end of the day lectures are of marginal use and really the learning happens when it's you and the textbook(s). I personally went back to school because it was a way of putting pressure on myself. There's a lot of boring drills before it gets particularly interesting. The biggest value of school/coursework for me was the fact that it was a declaration of "I am going to do this now, and there are external motivators (grades, exams) to ensure that I stay on track." That said, if I had it to do over again, for the money I spent, I wonder if hiring a graduate students/postdocs or even professors as tutors would have been better. I suppose that even then, when the material gets boring or time consuming it's easy to walk away, whereas if you invest time and money into a class you basically are in good shape to shame yourself into succeeding. (plus being in the academic environment helps to get a better sense of the broader landscape of material) Maybe you could find a buddy to work with, like people do with the gym or whatever to shame each other into staying on task.