Having just finished reading all five volumes of The Hitchhiker's Guide to the Galaxy (You need a really warped sense of humor to get all the way through.), I would like to share a couple lessons from it.
The Perfectly Normal Beast is a creature that stampedes in herds, much like bison (buffalo)...except that they appear out of thin air and stampede off into thin air again.
In fact, this IS perfectly normal. Most things come and go as if by magic. Like the hunters in the book, who take advantage of the one week stampede to get all the meat they can for the year, we also have the opportunity to grab as much joy and fulfillment of everything that passes or even stampedes through our lives.
It's up to you to make the most of every minute. Go get 'em.