This year, many of my students have told me that since they now do every workout at home, they’re gravitating toward quick, efficient routines. That’s why I’ve created this bodyweight upper-body workout, which will help build stronger shoulder, arm, and core muscles—all in less than 15 minutes. It also plays with your body’s own resistance to improve body awareness and mental endurance. For an extra challenge and spice, you can grab a light set of dumbbells (think 2 to 3 pounds). Otherwise, all you need is your body and some motivation. Your 4-week challenge: Every week this month (keep an eye out for a new workout every Monday), I’ll be sharing a routine that targets various parts of your body, all with some core work. By the end of the month, I encourage you to make core work a regular part of your weekly routine—whether that’s one day a week, three, or even daily. I can’t wait to hear how you do!