As buoyancy is not contrary to other characteristics of leadership, including decisiveness, accountability and performance standards, I don't ever think it can be self-defeating.
First, define your credo- the belief system of the organization. Secondly, define your real ambition, or where do you want to go as a collective community.
I believe that the establishment of a real ambition, a powerfully galvanizing and exciting vision of what a group is setting out to create, is vitally important.
One of my great mistakes coming up, since I was a kid from wrong side of the tracks, and fearful that I might be seen as wanting leadership-wise, was to be someone I was not.