Sometimes speakers need to talk about subjects that don't interest them much, especially at work. I believe this is harder for introverts, who have trouble projecting artificial enthusiasm. But there's a hidden advantage to this inflexibility: it can motivate us to make tough but worthwhile career changes if we find ourselves compelled to speak too often about topics that leave us cold. There is no one more courageous than the person who speaks with the courage of his convictions.