Preheat oven to 350° F. Prepare a 9x5 bread loaf pan with nonstick spray or parchment paper.
In a large bowl, gently whisk whole wheat flour, cinnamon, baking soda, baking powder, and salt.
In a separate medium bowl, whisk together zucchini, brown sugar, Greek yogurt, oil, eggs, lemon zest, and vanilla.
Add yogurt mixture to flour mixture. Using a spatula, fold ingredients just until moistened. Do not overmix.
Pour batter into the prepared bread loaf pan. Bake 50-55 minutes or until slightly golden and a toothpick inserted into the middle comes out clean. Enjoy!