At school, they told me: work hard now, and you'll go further & suffer less. I discovered there's an exception to the rule: Big surf hold-downs & xtreme freediving. If you follow that advice & your at your edge, that sh*t will literally get you killed, & you should do the absolutely 180 degrees opposite if you care to survive.
Tell us something surprising that you discovered [about your business/customers/problem domain]. Telling them something about your hobbies is at best not helpful and if "that sh*t will literally get you killed" a huge negative. Full Disclosure: I'm not affiliated with YC, but have successfully pitched investors.