Place chicken breasts in slow cooker. Pour salsa over chicken and sprinkle on taco seasoning. Cover with lid and set crock pot to low and cook for 5 hours.
***I recommend cooking on low so that the chicken does not get dried out.
When chicken is done, remove some of the juices using a ladle and reserve. Shred chicken using two forks. Mix with remaining juice. Add in reserved juice if desired.