Which facial exercise is the best for adding definition to the cheeks and for sculpting a jawline?

To be honest: Facial exercises and/or facial "yoga" can be a double edge sword. There is limited data that working out facial muscle is helpful from a cosmetics perspective and there is some suggestion that excessive facial movements lead to worsening cosmetic outcomes. Remember crows feet and brow lines come at areas of significant muscular activity ... Botox works in these areas by paralyzing muscle.