Never compare, get and keep in shape, eat right and learn to accept your beautiful naked body.
If you see your body as a tool rather than a symbol of attractiveness you should be able to change your perception and alter judgement thereby increasing confidence in yourself.
I think you could write a book on all these things.
Japanese people, while subjected to other nefarious forms of propaganda, are fortunate in that they grow up in a society free of the 'original sin' nonsense, unlike us in the west.