Naysayers and the rail cart/truck analogy?

A little while back I was listening to a MT podcast and Mark (I think) gave a great analogy about how when you are trying to move forward, you have some people helping you pull the cart towards the new goal/direction, some people in the cart having to be towed but happy to be carried, and then some people who are at the back trying to pull your cart backwards: the naysayers.  Then he went on to talk about how if you give to much air to the naysayers - some of the people you had in the cart can also jump out and join the naysayers in holding your cart back.

Can anyone help me find this podcast again.  was it "How to Handle Meeting Killers?"

kind regards

Karen