Before you lift a heavy object, think through your task. Decide where you're going to place the object and how you'll get it there. If an object is too heavy to lift safely, find someone to help you or make several trips carrying lighter weight.
When lifting an object from the floor, stand as close to the object as possible. Then kneel, resting one knee on the floor. Don't lift from a standing position with your waist bent or your knees locked.