Define "work"

[lillibet]

Elsewhere, someone was discussing the work that he and his partner are doing to improve/sustain their relationship and someone else commented that if a relationship requires work, then it may not be worth continuing. This led into a discussion of what defines "work," more generally. If you enjoy a process, is it work? If you choose to do something, is it work? Are activities you undertake in pursuit of a hobby work? If you get paid to do something, is that work? If the product of your activity mainly benefits someone else, is that work? What activities do not count as work? What is work?

EDIT: For those of you who enjoy conversations between dpolicar and me as a spectator sport, be sure to check out the comments.