Have you ever felt that your purpose is not what you want?

The are lots of stories that involve a “Chosen One”, somebody who is destined to fulfill a prophecy, save the human race, end a curse, or complete a dangerous quest for some sort of greater good. Often this character goes through phases of unwillingness or unhappiness about the duty to which they are fated.

I can see this happening in real life. Obviously the stakes are much lower, but the concept is the same. When a person realises their potential to do good, what do they do when following through requires them to give up their dreams?

For example, a student knows she is intelligent enough and has the resources to become a doctor. She genuinely wants to help people and would be proud to devote her life to improving the health of people in poverty. But what makes her truly happy is art. She is aware that being an artist wouldn’t make her a comfortable living, even backed up by a small ‘day job’, but obviously that is not important to her. What is important is that creating, viewing, discussing art makes her happy like nothing else does. But realistically speaking, her following her dreams isn’t going to make the world a better place, in fact it feels quite selfish.

I know that was quite long, so here is the question rephrased:
Has there ever been a time where you have had to make a permanently life-altering decision between happiness and duty?