In the traditional relationship between an individual and work (and this won't apply to those of you who have already found your vocation) there can be certain advantages to separating your work and your personal life.
Many of us have colleagues (past and present) whose interests outside of work have pleasantly surprised us. In most cases, we are not surprised because these friends have interests in extreme sports or Japanese sub-culture, we are surprised because the individual's personality at work gave us so little by way of clues.
The same relief that you feel when your interests are no longer completely hidden from view might be a taste what work/life fusion has the potential to deliver. Where your values, interests and ambition are increasingly represented in your profession, you are closing in on your vocation and a lasting, individual definition of success.