Great question. I see this etiquette standard broken quite a bit. Even in the movies, I have noticed that the honoree violates the toasting process. A toast is proposed to recognize the importance of an occasion or to bring to light the extraordinary deeds of a person or persons.
As glasses are raised in your honor, you should sit or stand quietly, smile accordingly and nod your head in appreciation of the recognition. If a toast is being offered to the bride and groom, they do not drink. Doing so would be the same as singing Happy Birthday to yourself, at your party.