01/13/2012 08:20 am ET Updated Dec 06, 2017

Yoga Journal 21-Day Yoga Challenge, Day 5: Core Focus With Rebecca Urban

Today's video champions the core -- the muscles around your abdomen, back and rib cage that help support and improve posture and alignment. It might be spot training, but it's highly integrative: your whole body will benefit from strength at its center.

When our partner Yoga Journal put out the call for their 21-Day Yoga Challenge, we knew we wanted to be a part of it. Over the course of three weeks, we're going to learn to incorporate a daily practice of breathing, meditation and vegetarian eating to our busy lives. We're hoping to emerge stronger, more flexible and mindful of the choices we make for our bodies. You can check out our progress at Team HuffPost's Social Workout page and you can follow along on our blog. Want to join the challenge? Click on the leader board below to become a part of Team HuffPost!