Why do we feel constantly tired?

Do you feel tired constantly? Even after waking up from a fully rested nap and you still wake up feeling tired. This is a condition that I have been hearing very often. I also have personally experienced this. I often wondered about this. Most people seems to just dismiss it as laziness or they seem to just accept that is who they are, as if that is their identity that they accepted as who they are. I hear this from my coworkers, family, friends. Everyone constantly feels tired. My coworkers would even say this to me in the morning at work. When they greet me, they would say “Good morning, I’m ready to go home, I’m tired”. Like we just got into work and you’re already tired? I get that they are trying to be funny, but this is what I am hearing from almost everyone.