As I'm making a professional transition from being a university lecturer in linguistics to being a self-employed life coach, the constellation of the languages I use in my professional life is also undergoing a fundamental reshuffle.
Being a linguist specializing in Hebrew as well as Yiddish and Esperanto to a lesser extent, I used to use these three languages as both objects and tools of my study. As I don't specialize in these languages any more, Esperanto has totally disappeared from my new professional (and private) life. Hebrew and, to a lesser extent, Yiddish serve me now as languages for classical sources of Judaism, especially (Chabad) Hasidism, and their contemporary commentaries, which I try to incorporate into my new practice of Jewish life coaching.
Though I received my BA and MA in Japan, few of my reading and reference materials then were in Japanese, so I never developed my professional lexicon and style in Japanese. As my new practice is meant for speakers of Japanese, I have the first opportunity in my entire life to use it professionally, though mostly orally in my interaction with Japanese-speaking clients. English remains as important as before as the main source of modern professional information and knowledge.
The biggest linguistic change in this professional transition is the change of my concept about language in general. I feel and experience more and more strongly that language is not only limited but also limiting. It limits us in that it keeps us trapped in the prison made unconsciously by our mind, which uses language as its main tool. Our mind itself is supposed to be our servant, but this servant has hijacked its master and has become the master itself.
In this new light I can't see any essential meaning for myself any more in the study of languages and language as is done in the so-called academic research. I see even far less meaning in the very idea of an international planned language such as Esperanto as a tool for unifying the humankind because of the above-mentioned limitation. Actually, we are already unifieded as divine souls. All we have to do is to become aware of this and transcend our ego, both individual and collective. For this purpose we also have to transcend our mind, hence language, too.
For similar reasons I can't help seeing, e.g., secular Yiddishism, as nothing but mental idol worship.