Hi What this means is to let ourselves be open to new experiences. Its a sort of idiom written by the author. If you were to stay indoors all day and every day you would never be exposed to anything and you would not learn, grow as a person or change etc: So we must willingly "throw ourselves out into the open" not literally throw yourself but just get out there and learn! Hope that helps :)

Just to add to Neil's explanation... I think the writer used a tactful turn of phrase - she could easily have written "...if we expose ourselves", which is technically correct, but that would create an unwanted double-meaning. The other meaning of "to expose yourself" means to show your naked body to people. She obviously wanted to avoid such a comical misunderstanding, and chose a more definite way of writing it. A good choice of words, too. There was an amusing poster from years ago, which used both meanings of "Expose yourself to Ireland": http://lacarmagnole.free.fr/images/Ireland.jpg