1. In a mixing bowl, combine Greek yogurt, olive oil, minced garlic, dried oregano, salt, and black pepper.
2. Add chicken breasts to the bowl and coat them well with the mixture. Let it marinate for at least 15 minutes.
3. Heat a skillet over medium heat. Cook the marinated chicken breasts for about 7-8 minutes on each side, or until fully cooked.
4. Remove chicken from the skillet and let it rest for a few minutes before slicing it into strips.
5. Warm the pita bread in the skillet for about 1 minute on each side.
6. Assemble the wraps by placing lettuce, tomatoes, cucumber, red onion, and sliced chicken on each pita. Top with crumbled feta cheese.
7. Roll up the pita bread to form wraps and serve immediately.