In a bowl, mix together Greek yogurt, mayonnaise, celery and salt.
Add chicken and blueberries to mixture. Mix well so that chicken and blueberries are coated in mixture.
In order to warm the tortillas, place a damp paper towel on a plate and add a tortilla on top of it. Create a stack, alternating Between damp paper towels and tortillas. Top the stack with a damp paper towel.
Place the stack in a microwave and heat for a minute
Placing lettuce leaf on top of each warmed tortilla.
Scoop generous amount of the chicken and blueberry mixture, and place it on the lettuce leaves.