Looking back, it wasn't because the material was hard, or boring, but because it was completely unmotivated. They may as well have been asking me to organize piles of toothpicks or count ceiling tiles to fill up the class periods. There was simply no sense to it.
I think this is partially understood, and the attempted solution is to try to find applications for the math you're learning. Except that once you hit even basic algebra, you quickly run out of applications a young student can relate to. So they go home, ask their parents "what do you use Algebra for?" and get "I don't." and that's that.
I think, along with application concepts, the history of these maths...why were they created, about the creators who came up with the concepts, what were they trying to solve, let's solve the same problems with these new techniques, etc. This would have grabbed me and pulled me in. Instead you sometimes get a little box in the reading quickly going over all this (if you are lucky) before a hundred problems are dumped on you to drill through. It's rarely talked about in class, and if it is, it's by a teacher who doesn't know or appreciate the value of this history at all.
By doing this you show applicability to entire fields, even if the child doesn't understand what's involved in the field. Those kids that say "when I grow up I want to be a biologist" will encounter stories about people who learned to apply logic or math or fractions or whatever to solve difficult problems in biology or whatever, and then relive those moments as they try to solve the same or similar problem using the tools they were just given.