What makes success?

(Alert! Boring publishing numbers post ahead. Escape while you still have your sanity!)

Publishing has not been easy for me. This is entirely my fault. I dove into the process with no research, and decided that I would sell my books by hawking them to strangers on Twitter and sending them to book bloggers.
 
Take a moment to laugh. I'll wait.
 
Unsurprisingly, it took three months to sell the first 100 copies of Six Moon Summer. That was about $200 in royalties. At the time, the number seemed huge -- it was more than I had made off of writing ever before, anyway, and that meant there were about one hundred people reading my book. Gosh. Never mind that I had spent $750 producing and marketing the damn thing.
 
Thanks to success stories from authors like Amanda Hocking and Joe Konrath, many writers dove into self-pubbing at the exact same time. YA paranormal is a pretty good genre to be in, too, so quite a lot of writers entered it simultaneously. It's not typically a blockbuster genre (I would reserve that term for things like romantic suspense), but it's got a loyal base of readers, good crossover appeal, and high churn. Readers who enjoy YA paranormal tend to devour it and look for more.
 
So while I was selling 100 copies on Twitter, writers who were producing the same thing at the same time were zipping ahead to much grander milestones. They were popping out entire trilogies and reaching upwards of 10,000 sales in six months while I was still tweeting "#yaparanormal #pleaseloveme Omgz buy my book!!! amzn.to/lololol".
 
Still, I felt pretty good about the whole thing. 100 books. That's a lot of readers.
 
All Hallows' Moon did about the same: 100 copies-ish in three months. Understandably. I had waited five months to release the sequel, which was entirely unnecessary, given that I had actually written Six Moon Summer the year before, and any miniscule amounts of momentum I had built were long gone by then.
 
Of course, I had other things going, too. The 19 Dragons trounced the other books for its first couple of months. Death's Hand came out shortly after All Hallows' Moon and sold over 1,000 copies in its first three months, which was a huge milestone for me, since it took six months to reach my first 1,000 sales prior to that (don't laugh).
 
I'll skip a long and boring history of the books in between that, but suffice it to say, things have improved. Gray Moon Rising sold 1,000 copies in about two weeks thanks to the efforts of my dedicated and loving readers.
 
This month, I have averaged 200 books sold per day -- twice what I sold in the first three months of publishing, every day.
 
I'm still struggling in comparison to many of my writer friends, who are all smarter, handsomer, and more successful than me. Many of my contemporaries have passed 50,000 sales or more. People in other genres are doing even better--one writer friend of mine, Michael Wallace, is celebrating 100,000 lifetime indie sales this month. (Congrats Michael! Feel free to send my helicopter over at any time.)
  
But how do you measure success? Is it in a specific number of copies sold? Are you successful when you've shifted 1k copies, 10k, or 50k? Is it when your income from royalties provides 50%+ of your family's income?
 
Or is it when those first 100 readers pick up your book and fall in love with the characters?
 
You know, I just don't think it can be measured in any objective way.
 
I'm feeling successful these days, even though I don't have any big-number milestones to trumpet. The line on the graph keeps going up, and every time I have a series release, I do a little bit better. That makes me feel successful.
  
Every one of my books has an actual team working on it, now--from artists to editors--and I actually earn out production costs within a month or so, which means I'll probably start spending more money on producing better books. That makes me feel successful, too.
 
I finished a series, and I'm pushing ahead on a second. I have nine titles out with this pen name now, which is staggering, and seven titles more than I had available in July of 2011.
 
But most of all, my writer friends and readers make me feel successful. Their relentless love and support never fails to touch me (in the safe & legal sense). You know who you are. ;)
 
For my writer friends: How do you measure your successes? Is it a specific milestone, or net increase in performance?