Well, historically, childhood bullying/rejection for learning disability, and then being a chubby kid. Since lost the weight but still have the fear of rejection.
In the last few years I have been difficult for any counsellors to deal with because I keep rejecting the basic concept of self esteem which would allow me to except myself being e.g. chubby again/not lean. I've developed the belief that self esteem and self acceptance is erroneous and illogical considering that I really believe each person's value is conditional. Self esteem is mostly an illusion created by our egoes. More objectively (although everyone's experience of mortal consciousness is subjective) since we are granted life, our duty in return is to:
1) make the world a better place which can roughly be summed up as:
a) improve ourselves to become the best tool possible for the maintenance and benefit of the state (i.e. our job skills, careers-a;though I disagree with capitalism to an extent this is the easiest compromise we can make under the conditions of the 21st century)
b) improve ourselves to become the best, most useful tool for the benefit of the community (which can include the local population but also more close-knit communities such as friends, family, neighbours etc.; this I guess would be our personality?)
2) Improve ourselves to be the possible donor towards the 'gene pool' as it were for the benefit of the continuation of the human race. This involves the theory of sexual market value (attractiveness) not limited to but including physique/aesthetics, wealth, social proof (social status) etc.
It draws similarities with the popular 'alpha male' hypothesis in evolutionary psychology, especially explaining why men are considered the disposable gender. At times it moves towards fascist eugenics theory (especially the 'gene pool' thing ugh). However that is justified by the evo-psych element.
I really have little choice but to improve myself as to be more useful (whether to romantic/sexual partner, friends/family, employment, community etc.)
It's a cynical replacement to my old religious beliefs in Christianity, where I was saved from my imperfection by virtue of God's unconditional love. Wish I could go back there but I'm too far down the existential ladder now to return without a long hard climb through theology, science and philosophy.
When I had that I still advocated self improvement but I was a bit more forgiving of myself for when I made a mistake, or didn't match up to certain social expectations, or was out of shape. So my confidence, although a little lower than most, was free from any serious crisis.
I'm going to make a thread soon about it. It's a bit of a scary theory to believe in though, I am yet to share it to my family or friends :/
What made you lose your self confidence?