Women who start out as ugly ducklings don't become beautiful swans. What they mainly become is confident ducks. They take charge of their lives.
I don't think you're happier if you're thin or beautiful or rich or married. You have to make your own happiness. My heroines do not become beautiful elegant swans, they become confident ducks and get on with life.
I don't have ugly ducklings turning into swans in my stories. I have ugly ducklings turning into confident ducks.