Going cold turkey

Going cold turkey in early drug slang referred to suddenly and totally stopping drugs. The term is now used in general slang with the broader meaning of stopping any habit or practice suddenly.

Allegedly, the term "cold turkey" comes from the comparison of a cold turkey that has been refrigerated and the state of a withdrawing addict, the cold sweats and gooseflesh.

Example sentence:
Doctor says that you can't just go cold turkey in your situation. We have to move gradually.