From a standing position pick up a weight, kettle bell or heavy briefcase/bag. The weight should be heavy enough to be challenging but not so heavy that you cannot grip the weight and risk dropping it or you are not keeping good form. As per all of our core moves start with a good core brace, a shoulder blade/scapular set and a packed neck. With your chest raised high simply start walking. You should immediately feel the weight trying to pull you toward its side. As a result your opposite side will contract quite hard to stabilize and protect the spine. Try to walk for 60 seconds. If you feel fatigued prior to 60 seconds or your grip is giving out simply set the weight down (Properly! Mind your back position!) and rest for 10-15 seconds. Time yourself, if you were less than 60 seconds then build up to a goal of 3 sets for 60 seconds each with a weight that is heavy enough to make the last 5-10 seconds quite challenging.