Heat olive oil in a large heavy-bottomed skillet or wok over medium-high heat until shimmering.
Add chicken strips in a single layer, season with salt and pepper, and sear for 5-6 minutes until browned and internal temperature reaches 165°F (74°C).
Remove chicken from the skillet and set aside on a plate.
Add red bell pepper, zucchini, and red onion to the skillet and stir-fry for 4 minutes until vegetables are crisp-tender.
Stir in minced garlic, oregano, and thyme; cook for 60 seconds until fragrant.
Pour in chicken broth and lemon juice, scraping the bottom of the pan to release browned bits.
Return chicken and any accumulated juices to the pan, add Kalamata olives, and toss for 2 minutes to combine and heat through.
Remove from heat and garnish with crumbled feta cheese immediately before serving.