You have to be there not for the fame and glory and recognition and being a page in a history book, but you have to be there because you believe your talent and ability can be applied effectively to operation of the spacecraft.
Whether you are an astronomer or a life scientist, geophysicist, or a pilot, you've got to be there because you believe you are good in your field, and you can contribute, not because you are going to get a lot of fame or whatever when you get back.