The answer is Ultraviolet Light
The easiest way for us to obtain a sustainable amount of Vitamin D is by exposing our self to morning sunlight ( which contain ultraviolet light)
Often time, we don't consume enough vitamin D and our body need to get it from our bones, and in order to do that, it need to be activated through enough exposure from sunlght
Answer:
Science plays a rather large role in the modern world. Without it, devices such as phones, computers, and even TV wouldn't exist. With advances in science, humans have been able to cure many ailments and diseases that were previously incurable.
It kind of stretches and once you excrercise a lot your muscles could get sore but for the next time you'll be much stronger and healthy:)