In a medium mixing bowl, whisk together the Greek yogurt, olive oil, minced garlic, lemon juice, lemon zest, oregano, paprika, salt, and black pepper until well combined.
Place the chicken breasts in a large resealable plastic bag or a shallow glass dish and pour the marinade over them, ensuring all surfaces are evenly coated.
Seal the container and refrigerate for at least 30 minutes, though 4 hours is recommended for optimal tenderization.
Preheat a grill or heavy-bottomed cast iron skillet over medium-high heat and lightly oil the surface.
Remove the chicken from the marinade, shaking off any heavy excess, and place onto the cooking surface.
Cook the chicken for 6 to 8 minutes per side, depending on thickness, until the internal temperature reaches 165°F (74°C) on an instant-read thermometer.
Remove the chicken from the heat and let it rest for 5 minutes before slicing to allow juices to redistribute.