One Thing You Can't Do in Heaven...

Last night at church we listened to a speaker named Mark Cahill. He lives near Atlanta and is an author and speaker. One of his books is titled, One Thing You Can't Do in Heaven. Over the past few months I'd heard a few people at church mention the book but didn't give it too much thought. I was a bit curious what that one thing was, but didn't pursue it.
This guy has amazing stories to tell about the conversations he's had with people concerning eternity and what's "on the other side". He's spoken with Charles Barkley (one of his college roommates), Micheal Jordan and Tiger Woods to name a few. All of these are mentioned in the book. Anyway, I intend on beginning the book soon...the website is www.markcahill.org. His materials are well worth looking into! One of his simple truths is "If they're breathing, they need Jesus."
So...what's the one thing you can't do in heaven?
Tell people how to get there!