The first sentence sounds inauthentic. Did you really talk to yourself? Did you even think
that quote to yourself? Probably not. More than likely, you pondered at your desk staring at the ceiling rubbing your chin while thinking about your goals. Saying you talked to yourself is just strange. In short, it's not real, it's theatrical. And there's a huge difference between the two.
You can be informal and "real" without being cutesy. Your second sentence is off-putting because it sounds exaggerated (few bosses are caricatures, even if you think they are). Also, what's consistent
about being exuberant at times and suicidal at others? Unless you're being sarcastic, in which case, it's not "real", it's just "mean". Moreover, the "at least" part in your sentence smacks of sarcasm and immaturity. It sounds more like something I'd say to a bunch of guys at a bar after a tough day at work, than an inspired story about leadership.
Sorry to be so blunt but that's what I get from this. Striving to be yourself doesn't mean "try at all costs to be a wild-card and not sound like a robot". It means talking in a voice that you feel comfortable with.
My blog: http://www.theapplicationist.blogspot.com/
My application status: 2012-profiles-w-admit-dings-results-no-discussion-116595.html#p983273