01/03/2011 02:34 pm ET | Updated May 25, 2011

Hugh Hefner, Crystal Harris Talk Whether He'll Have More Children, Wedding

Hugh Hefner, 84, is marrying Crystal Harris, 24 in what the couple says will be an "intimate affair." Will they start a family together? Don't count on it -- but don't count it out.

"Well, we'll see. That's not part of the big plan," he told Entertainment Tonight in an exclusive interview. Of course, the question behind that question is, well, can he even do that? Remember, a former Playmate alleged that he had a bit of difficulty with that.

"I'm doing my best. Dancin' as fast as I can," he laughed. For her part, Harris thinks he has plenty of vigor.

"I don't notice the age difference with Hef at all," Crystal says. "If anything I have to keep up with him."

For much more from the interview, which airs Monday night, click over to ET.