Everyone always says to write what you know, what you've experienced, what you've personally gone through. What a load of crap! Granted, I always tend to interject some military, in one form or another, into my stories. But, that's what I like to do. That being said, if you only write what you know, how will you know if that's the only thing you like?
The short and sweet answer is that you don't.
I want to challenge you to get out there, learn something new. Get outside of your comfort zone, read up on something that you didn't know before and then go and tell someone about it. Find something and become passionate about it.
What a lot of you don't know, and some of you do, is that I have been a member of the SCA (www.sca.org) for well over a decade now. It's an international society that recreates (NOTE: not reenacts) the medieval period. When I first started, I picked a persona that wasn't for me. I didn't like it, but I went along with it because my now ex-husband was doing it. I then moved on to researching the Mongol culture and really enjoyed it. However, that was suggested to me, and still didn't fit me. It wasn't until I found the Ancient Romans and started to look into them, their culture, textiles, and cooking techniques that I was really hooked. I look forward going to events, spending time with my friends and talking about our shared interests, and talking to anyone that wants to listen.
It's similar to that. Find something you like, that something that could spark your interest, and fan that flame. Let it grow and run with it. Don't write the same things over and over again. Find something new and exciting. Share that excitement with your readers.