“None are so old as those who have outlived enthusiasm.” – Henry David Thoreau

This quote is a subtle reminder of the power of enthusiasm. The ability to motivate team members, investors, your early evangelists etc. depends to a large extent on the natural (not the faked type) of enthusiasm that founders radiate. It therefore is one of the important signals I look for when working with founders and colleagues. A little spark in your eyes when you talk about your cause!