Thaw and clean chicken breast and place in bottom of slow cooker, pour jar of salsa over chicken and turn slow cooker to low. Let cook for as long a needed to cook the chicken (depends on thickness of the breasts).
When chicken is done remove the chicken and shred it, place back into slow cooker.
Cook rice. As much as you need. I cook 1 1/2 cups dry for my family of 4. If you use brown rice it takes about 40-45 minutes to cook. Keep this in mind when for having your rice done about the time your salsa chicken is ready. Using brown rice keeps this healthier than using white rice.
When rice is done spoon salsa/chicken mixture over rice and mix, or mix rice into slow cooker. You can mess up the healthiness by adding cheese which is what my husband does. :)
Adjust amount of chicken, salsa and rice by the number of people you will be serving. My listed amounts are for my family of 4.