Mix salsa, lime juice, taco seasoning, and cilantro in your slow cooker. Place chicken breasts on top of the salsa mixture and sprinkle with garlic salt and pepper.
Spoon salsa over chicken breasts, cover, and cook on HIGH for 3-4 hours or on LOW for 7-8 hours.
Once done, remove the chicken from the slow cooker and shred it with forks and return back to the slow cooker. Set to warm and serve from the slow cooker.