Preheat the oven to 350℉ and set the rack to the middle position.
Heat a sauté pan over medium-high heat and add the walnuts. Toss them for about 2 minutes or until they're fragrant and start to turn golden. Remove them from the heat, chop them, and set them aside.
Trim the ends off the zucchini, then use a box shredder or a food processor fitted with the grating blade to shred it. Lay the shredded zucchini on paper towels and squeeze it to remove the excess water. Set this aside.
In a mixing bowl, combine the flours, baking soda, baking powder, salt, cinnamon, and lemon zest. Use a whisk to mix the ingredients well.
In a second mixing bowl, whisk the eggs, then add the honey, olive oil, yogurt, and lemon juice. Whisk everything until combined. Add the zucchini and mix again.
Add the dry ingredients to the wet ingredients, and use a spatula to mix well, scraping up any flour from the bottom and sides of the bowl. Add the nuts last so they stay suspended in the batter. Make sure everything is combined, but don't overmix or the batter will be tough. Let the batter sit for 3-4 minutes to allow the flour to hydrate.
Spray a 9x5x3-inch loaf pan liberally with cooking spray (do this even if it's non-stick). Transfer the batter into the loaf pan. Bake the zucchini bread for 45-50 minutes or until a knife or toothpick inserted into the middle comes out clean.
Let the loaf cool in the pan for at least 10 minutes, then run a knife around the edges of the pan, invert it, and gently remove the lemon zucchini bread. Let the loaf cool on a cooling rack for at least one hour before slicing.