It is one of the things which fills my soul with joy and just makes me feel like I am a human being who actually is living. The theological reason for this I see in God giving Adam work even before the Fall, meaning that the self-exertion is in itself good. I consider it to be one of the natural peaks of human experience, which include but are probably not limited to: being productive (all work falls under this, so does generating and raising childre), being creative (has overlap with the former, but I mean creating art mainly or beautifying things and imposing rational order onto raw matter), loving in a relationship (God and man, for instance practicing mental prayer or spending time with family and friends), and experiencing/receiving beauty (like passively enjoying nature and such). I had thought of more but that is the reason. Reducing these things just leads in my opinion to a loss of self-worth among other things.