Quoting Benjamin Todd:

The hope is that, deep down, people know what they really want.
However, research shows that although self-reflection is useful, it only goes so far.
You can probably think of times in your own life when you were excited about a holiday or party — but when it actually happened, it was just OK. In the last few decades, research has shown that this is common: we’re not always great at predicting what will make us most happy, and we don’t realise how bad we are. You can find an overview of some of this research in the footnotes.1
It turns out we’re even bad at remembering how satisfying different experiences were. One well-established mistake is that we often judge experiences mainly by their endings

This means we can’t just trust our intuitions; we need a more systematic way of working out which job is best for us.

Many successful people are passionate, but often their passion developed alongside their success, and took a long time to discover, rather than coming first.