形容詞 by choice:

1. not by chance

副詞 by choice:

1. with intention; in an intentional manner
   同義詞：intentionally, deliberately, designedly, on purpose, purposely, advisedly, by design

1. He has grown interested in graphic education first by force of circumstance but later by choice.
   開始由于形勢所迫，但后來出于自己的選擇，他逐漸對書畫教育感興趣起來。