under own steam 自力で

under one's own steam は蒸気船が自力で動くこと。転じて人の手を借りずに自力で物事をするときに使われる。 2:12 she's bounced back from surgery. 7-year old Kimberly is up and walking under her own steam. キンバリーちゃんは術後、一人で歩いた。

A Giant Floating Naval Hospital's Amazing Humanitarian Work

https://www.youtube.com/watch?v=rpy2NLwvs7Q  0:56 I'm going to be 81 shortly. and I'm still going along under my own steam. もうじき81になるが、まだまだいける。
Cardinal Edward Egan Discusses New Pope Jorge Mario Bergoglio

練習問題解答
a-9954 sailing under its own steam