Motivation is strongly tied to success.
Success cannot be given. To be felt, it must be earned. (yeah, I came up with that!)
The Houghton-Mifflin style of math textbook that I grew up with does have its drawbacks, but it works well to motivate kids to success. Each day a new skill is taught and then the day's work is to practice that skill. Learning and applying a new skill is a success reward on its own. The teacher is free to meet with students individually and to answer questions, and the student gets practice applying the skill. Highly functional.
The current book that I'm using (the CMP2 textbook series) does much to tie big ideas together, thus making the skills learned meaningful. However, it does lack some in the motivation department. In Looking for Pythagoras, the book has students proving that a general case of the Pythagorean Theorem works before they understand how cool it is, or what it even does. Transitions are missing: Too much learning is heaped on without time to build up to it, and it is not easily accessible as an "I-just-want-to-learn-it" tool.
However, the CMP2 series is generally better because of the story-like approach it gives to each lesson. There are deeper questions early on, that require deeper understanding of the subject being taught. And it does provide practice problems at the end of each chapter. In addition, CMP2 books are much lighter, since they are broken into mini-units.
Although I am coming to a realization here about how motivating it is to learn, and how teaching a single separate skill each day is functional in the classroom, I am stuck with the CMP2 series, and I now just need to try fixing my teaching style to increase that motivation.
And I need to keep waking up with this kind of epiphany.