The phrase "doing in to" can have a variety of meanings, depending on the context in which it is used. Some synonyms for this phrase could include "getting involved with," "entering into," or "embarking upon." These phrases all suggest taking an active role in something or committing oneself to a course of action. Other synonyms might include "taking on," "undertaking," or "assuming responsibility for." Whatever the specific meaning of "doing in to" in a given context, it always implies participation and engagement, rather than passivity or disinterest.