We don't always have an accurate view of our own potential. I think most people who are frightened of public speaking and can't imagine they might feel different as a result of training. Don't assume you know how much potential you have. Sometimes the only way to know what you can do is to test yourself.
Winners are people who have fun - and produce results as a result of their zest.
Working for a federal agency was like trying to dislodge a prune skin from the roof of the mouth. More enterprise went into the job than could be justified by the results.