Lay the chicken breasts flat in the slow cooker in a single layer.
Stir the cumin, garlic powder and salt into the salsa, then pour it over the chicken so every piece is coated.
Cover and cook on low for 4 hours. Do not lift the lid and do not run longer; set a timer.
Check the thickest breast reads 165F, then shred the chicken directly in the cooker with two forks.
Stir the shreds back through the liquid and let them stand 10 minutes on warm so the meat drinks the salsa back in.
Serve in lettuce cups, over cauliflower rice, or in warmed corn tortillas, and count whichever base you choose.