According to Osho, the heart you think you have is only accumulated past - antique emotions and borrowed sentiments - so the master takes it out. When that inner junk is removed, nothing fixed remains to be found; in that emptiness the truly new can arise. Drop old identities and become present, allowing a fresh, living heart to be born each moment.
Your old heart is like a dusty closet; clear it out so a fresh, living heart can appear now.