Let's Talk About.. HIIT (High Intensity Interval Training) vs. Hours in the Gym...
I don't know why this comes to mind when thinking about HIIT... Maybe because it involves a lot of planking and core strength? Regardless, I can say that after 3 weeks of doing the Jillian Michael's HIIT 30 minute videos, I'm getting much closer to the top picture vs. the bottom picture from when we first started.