Heat a large skillet over medium heat until the olive oil shimmers and smells fragrant.
Add the cooked chicken to the skillet and cook, stirring occasionally, for 2-3 minutes until heated through and slightly golden.
Push the chicken to one side of the skillet and add the sliced zucchini to the empty space. Cook for 4-6 minutes, stirring occasionally, until the zucchini develops golden edges and is tender but still has a slight bite.
Add the minced garlic to the zucchini and cook for about 30 seconds until fragrant, stirring constantly to prevent burning.
Mix the chicken and zucchini together, then sprinkle with chopped thyme or parsley. Squeeze lemon juice over the skillet and cook for another 2 minutes, stirring to combine all flavors.
Taste and adjust seasoning with salt and pepper as needed. Remove from heat and let rest for 2 minutes to allow flavors to meld.
Serve the skillet directly from the pan, garnished with extra herbs or lemon zest if desired, and enjoy this cozy, flavorful meal.