Why is this the answer?

The answer is boots because this clever riddle describes the life of the shoes you wear almost every single day. Imagine your favorite pair of hiking boots or even your comfy school sneakers. The riddle starts by saying, "Two brothers we are, great burdens we bear." This is a tricky way of saying that you always wear two boots, one on each foot. They are a pair of "brothers" that are always together. They have to carry a "great burden," and that burden is you. All day long, your boots hold up your entire body weight, whether you are walking to school, running to catch the bus, or playing tag outside. Think about how much work that is for two shoes to do! They are working hard all day to keep you moving and standing tall. Then the riddle continues with, "All day we are bitterly pressed." What is inside your boots that is pressing on them? Your feet, of course! Your feet are squeezed inside the shoes all day, especially when you move around a lot. This pressing is how the boots stay securely on your feet and protect your toes and ankles from bumps. Finally, the most important clue is, "we are full all the day, and empty when go to rest." This tells the whole story of a day in the life of a boot. Your boots are "full" of your feet from the time you put them on in the morning until you take them off at night. But as soon as your busy day is over and you are ready "to go to rest," you take your feet out. The boots are left standing empty by the door or in the closet, waiting patiently for the next morning. This is a wonderful secret that the boots keep about when they are working hard and when they get to finally rest. They are full when working and empty when resting, which makes boots the perfect answer to this awesome word puzzle.