Preheat indoor or outdoor grill to medium high heat.
Place cumin, salt, pepper, paprika and garlic salt into a bowl.
Whisk seasonings to combine.
Place chicken breasts into a large bowl or large zip-loc bag.
Pour seasonings, and oil over chicken then squeeze the juice of one whole lime over chicken and seasonings. Stir chicken around with the seasonings and lime.
You can marinate up 1- 5 hours if desired. Can be grilled immediately as well.
Spray grill lightly with cooking spray then carefully place chicken onto grill. Let grill 5-6 minutes each side, or until cooked through and juices run clear.
Transfer chicken to a large plate and let rest for 10 minutes, covered or wrapped in foil.
Thinly slice chicken and squeeze with juice of last lime over top.