Crockpot Chicken Tacos

4-6 boneless chicken breasts
1 16 oz. jar of salsa
1 cup fat-free sour cream
shredded lettuce
diced tomatoes
shredded reduced-fat cheese
whole wheat tortillas

Place chicken breasts in crockpot and cover with salsa.  Cook on low for 6-8 hours or on high for 4-6 hours.  Before last hour, shred chicken with two forks and add one cup sour cream.  Let cook for one more hour.  Serve on whole wheat tortillas.