Stir together all of the ingredients for the marinade.
Add chicken to the marinade, toss to coat, cover tightly, and chill for at least 30 minutes (or up to two hours for more added flavor).
While chicken is marinating, stir together all ingredients for the cucumber salad. Set aside.
Use tongs to transfer marinated chicken to a preheated cooking surface (grill or skillet) and cook for 5-6 minutes on each side over medium heat until cooked through.
Arrange the pitas on a plate or clean surface. Assemble the pitas by filling pita bread with lettuce, chicken, cucumber salad, feta cheese, and tzatziki sauce.
Fold the pita over like a sandwich or roll it up. Enjoy!