Older/Lazier

Does it have anything to do with age when we tend to stick to our comfort zone stronger than we used to? I often find it interesting knowing new people, learning new things, being in different places. Now I don't find it exciting. I wish I could just stay home and do little art at my own peace. I find it exhausting trying to catch up with the world. Even listening to a talk is tiring to me. Forming a smile is one tough job already. I doubt what is happening to me.