Combine the yogurt, lemon juice and chopped mint in a small bowl: set aside.
Spray a large nonstick skillet with nonstick spray and set over med heat. Add meatball and cook , coverd , turning frequently, until heated through ( if using fresh ground turkey make sure its cooked and no pink is left about 10-15 minute) which will add to the cooking time.
Cut a pocket in the pita. Fill each pocket with 3 meatballs, about 2 tablespoon of the tomato, about 2 tablespoon of the cucumber, and about 2 tablespoon of the yogurt mixture, and mint leaves (if using) Serve at once.