2 (6 ounce) cans light water-packed albacore tuna, drained and flaked
1 large red apple, chopped
1/3 cup chopped celery
1/3 cup raisins
1/3 cup chopped dates
1/4 cup chopped walnuts
1/2 cup fat-free plain yogurt
1/4 cup reduced-fat mayonnaise
4 lettuce leaves
1/4 cup shredded reduced-fat Monterey Jack cheese