Your core muscles (including your abs!) are perhaps the most important muscles in your body — they help stabilize your spine, in turn allowing you control over your head, neck, and pelvis. But when it comes to actually strengthening your core, it's easy to get intimidated. That's why we partnered with fitness expert Albert Matheny of Soho Strength Lab and Promix Nutrition to design a simple exercise challenge that will get you on the way to a stronger mid-section in only three weeks. And with each day's workout taking only about 15 minutes, everyone will be able to find time for this challenge! Sign up to get regular reminders, exclusive tips to improve your workouts, and so much more.