In a medium skillet, heat the olive oil over medium-high heat. Add the red bell pepper and zucchini and cook until crisp-tender, about 3 minutes. Add the spinach and chicken and cook until heated through, about 3 minutes.
Meanwhile, place the tortillas between 2 damp paper towels and microwave for 15 to 20 seconds.
Fill each warmed tortilla with one-quarter of the vegetable-chicken mixture. Top with the queso fresco and roll up to serve.