Daily Chinese Idiom Guessing Game
To undergo a complete transformation, shedding old traits and adopting new ones, often in a positive sense of rebirth or renewal.
原为道教用语。指修道者得道以后，就转凡胎为圣胎，换凡骨为仙骨。现比喻通过教育，思想得到彻底改造。
宋·释惠洪《冷斋夜话》卷一然不易其意而造其语，谓之换骨法；窥入其意而形容之，谓之夺胎法。”
After years of hard work, he completely transformed himself, undergoing a total change in his lifestyle and thinking.