There are times in your life where you are expecting a certain outcome and you end up getting something completely different.
Take a training course, for instance. You begin the course with the pretty rational expectation that you will walk out knowing more about the topic of the training. You may, or you may not. But at the end of the day you realise that the most valuable part of the day was meeting the other participants, who end up opening doors for you and connecting you with others.
Always keep an open mind. You may not get what you want, but you could get what you need.