I have to say I think it's a gendered thing. How many men do you hear saying 'I got lucky'...? Women are used to minimising their accomplishments. So maybe we should just start saying 'Hell yeah I did it cos I'm awesome!'
So true. I was raised to worry about "bragging" and "showing off" — both my parents had considerable achievements that they downplayed, and my dad even made it a point of pride not to put a sticker from my fancy college on his car. (Maybe that's a Midwestern reverse-snobbery thing.) Anyway, now I struggle to find ways to acknowledge achievement that won't be perceived as flaunting it.