<p>“do you think it will seem important enough to the reader?”</p>
<p>That’s entirely up to you as a writer. It’s easy to take an aspect of ones life that really is important and waste it by telling it in a maudlin or arrogant fashion. Likewise, as you’ve already mentioned, a good writer can start with something that might seem small and help the reader discover the profundity in it.</p>
<p>So far, people on this thread have been framing your topic as “changing your major,” which of course makes it sound like a typical thing to do. But it’s certainly possible that a switch from the sciences to the humanities represents not just a change of interest but a change of world-view. Frame it that way, and it <em>could</em> be central to your life – for all I know, the culmination of an existential crisis that kept you awake for months. It’s all in the telling.</p>