Opinion: Have you ever picked up a light box and thought, “That was easy!” While you might be happy that it was a breeze, you probably realized you would not get any stronger if you only lifted that light box. To get stronger, you would need to lift a box that was somewhat challenging. Of course, you don’t want to immediately lift a “too heavy” box even when your goal is to get stronger. Something too heavy could potentially cause a strain or an injury.