It's taken me years to actually like my breasts, I'm an A-Cup and I used to be very upset about that.
In highschool all my friends had beautiful, large breasts and it emphasized my dislike for my own.
I've always known that with my height and weight it would not have looked good if I had big breasts but I couldn't help envying girls with large breasts.
But I've now realized that, unlike one of my friends who really has huge breasts, I can wear whatever I want, I can find gorgeous lingerie more easilly (and I can wear all shapes of bras) and it's actully far more comfortable ^^
But I don't think it's easy to feel good with an A Cup when you constantly see pictures of women with rather large breasts and you're told "these women are beautiful !"