At long last I've started practicing life coaching as a coach as part of both curricular and extracurricular activities in Yiddish and Japanese respectively.
The school where I study life coaching in English this academic year offers six supervized practicum groups - five in English and one in Yiddish. Though my English must be much better than my Yiddish both lexically and stylistically, I've opted for the Yiddish practicum group as I feel far more comfortable with Yiddish than English emotionally. Though I have quite a few chances to speak Yiddish here in Jerusalem, I've never lived in any anglophone country, so English remains a tool of intellectual communication for me. On the other hand, I spent two full intensive years speaking Yiddish for not only intellectual but also emotional purposes. As life coaching has more to do with emotions than intellect, I simply don't feel comfortable enough coaching someone in English.
Do I also feel more comfortable with Japanese than English? Definitely! The former is my first language chronologically. But I'm not sure if I always feel more comfortable in Japanese than Yiddish emotionally. My true first language is a northern dialect of Japanese, which is quite different from standard Japanese, which is the variety I still use. But I haven't had so many emotionally intensive direct experiences in this standard Japanese. In a sense it remains a tool of intellectual communication though not in the same degree as English.
This self-introspection has lead me to a conclusion that has also surprised even myself - Hebrew has already become my present first language in that I feel more comfortable with it both emotionally and intellectually than any other language, including English, Yiddish and even Japanese.
In spite of this special "status" of Hebrew for me I've decided to target speakers of Japanese of my future practice of Jewish life coaching, which incorporates teachings of Chabad Hasidism, mainly because they seem to benefit more from this practice than speakers of Hebrew. Another factor is that there must be enough Hebrew-speaking Jewish life coaches, but I may be the only Jewish life coach who can also speak Japanese.