I realized after getting a degree in engineering from CMU that I should've loved biology so I went back to school after working as a software engineer for a year and studied neurobiology. And since then, I've suggested that people early in their career should take a break and go back to school and study something totally different.
In Zen and the Art of Motorcycle Maintenance Robert M. Pirsig suggests something very similar. He makes the point that students should go and work a job before picking what to study because they'll see where the value comes from (he of course puts it in much better words)