No need to be embarrassed, it's not an uncommon thought, although, of course, not good for you either.
The fact that you realized your negative thinking on it immediately is a good thing and that's progress!
I know it seems silly, but turning your thinking around to speaking to yourself in a more positive way is a big deal. It really does help. It's not about "fooling" yourself in to believing something you are not, which irks people who are practical, it's about being realistic.
I'm sure you have tons of good traits, how often do you tell yourself about those? When is the last time you thought, hey, I am a nice person, i'm kind, i'm fun, I want the best for other people. Hey, I look good today!
It's not about being self-centered, it's about having at least a balanced view of who you are.
Anyway, just my thoughts, glad you are posting!