How to Strengthen the Core (10 Minutes). In today's workout I teach you how to strengthen your core (abs) seated in a chair. The exercises in this video get progressively harder. To assist those with hearing impairments to understand what's being said in these videos, all videos created from now on will include closed captioning. (This will also be good for those who can't understand my accent, and for those who just want to turn off my voice 😄)! Enjoy the workout and let me know how you go! -