"Doest one bit" is a phrase that implies a complete lack of effort or interest towards a particular task or situation. To find antonyms for this phrase, we need to look for words that suggest enthusiasm, passion or dedication. Some antonyms for "doest one bit" could be words like "wholeheartedly," "passionately," "zealously," "earnestly," or "ardently." Using these words would convey a completely different attitude towards the task or situation at hand. For example, instead of saying "I don't care about this project one bit," using an antonym we could say, "I'm passionate about this project and will work on it wholeheartedly.