Pound chicken breasts to an even thickness of about 1/2 inch. Place chicken in a zip close bag with olive oil and greek seasoning. Smoosh around to evenly coat with seasoning and olive oil and let marinate for about 10-15 minutes.
Heat grill or George Foreman grill, and grill chicken till internal temp reaches 165 degrees (approximately 5-7 minutes on a George Foreman).
Remove from grill,place on plate then loosely cover with foil and let rest for 5 minutes before cutting.
Slice chicken into strips.
Construct pita sandwich as you desire, with spinach leaves, tzaziki sauce, feta cheese and Sun Dried Tomatoes with Greek Oregano.