The 30 most important minutes of your life may just be your dream business school interview. Some might say that's a crazy statement. Some may say that their wedding, or being at the birth of their first child is more important... and with that I can't argue. So perhaps I should say "the 30 most consequential minutes of your life." Perhaps no other half hour will ever have a greater impact on the rest of your life. If you completely mess up your wedding vows and stumble through the ceremony, your marriage will probably still end up the same in the long run. If you pass out during childbirth, your kid will turn out the same as well. If you mess up on a significant job interview, promotion board, or major business pitch, there can always be another just down the road. There are opportunities to recover. But if you mess up on your interview at a place like (insert dream school of your choice) there really isn't a second chance for most of us. Furthermore, the difference between getting admitted to a place like (insert dream school of your choice) or not can have cascading and hugely consequential effects on the rest of your life such as your business network, personal and professional development, lifelong career partners, even choice of career fields, and of course, career success.
It's no wonder many are extremely nervous before their interview. On the other hand, if you're not a little nervous, you are probably not taking it seriously enough.
I took my HBS interview extremely seriously. Or at least it was serious for a guy like me, as I have very little formal interview experience. I'm used to proving myself by my actions, not by my words. I spent three days in Cambridge, talked to many students, visited four classes, and rehearsed for many many hours. This was on top of several weeks of preparation. It was also the last interview I did, which proved extremely helpful. Of course, I don't know if any of this helped, but I certainly would not have risked doing any less in retrospect. There are two things you must be for your interview: confident AND prepared, which are two states that don't always come together.
I'm not revealing some great insight here, but rather relating the seriousness with which I took my HBS interview. If you are fortunate enough to be invited, consider it if nothing else, among the 30 most consequential minutes of your life. There are no second chances.