Why pose nude?

Why become a life model? After all standing in a room naked while everyone else is clothed and looking at you could be seen as quite a strange thing to do. Does it come from a simple love of art and a desire to be part of that art? Is it because the work's often cash in hand and relatively well paid? Do models feel that they themselves are artists and part of the creative process? Or is it something to do with exhibitionism, being seen or noticed? Perhaps some models are judged fat or ugly in everyday life and modelling gives them a chance to be accepted? Click on the above link for more info.