I think, and it’s just my opinion, that the self-help movement has left us expecting unrealistic things. Of course everyone has a feeling of insecurity at times. Everyone doubts their abilities on occasion. And the key to beating low self esteem is not to go around frantically thinking great things about yourself all the time.
If you expect to feel great about yourself all the time, then you will be disappointed. If you allow for the fact that sometimes you’ll feel low and just let it pass, it won’t last as long and you won’t feel as bad.