How do i feel zero pain after breast reduction surgery?

Following : your doctor's advice, possibly tight wrapping of the chest/breasts. Keeping the incisions clean. Zero pain may be an unrealistic expectation.

Zero? As in none?: Not likely unless a patient is very good with mind-over-body. Surgery means cutting and stitching things back up. That means the body will heal up through some inflammation. All that will generate nerve signals that people usually perceive as pain. Good surgical technique, good non-addictive pain meds, good luck, and a good patient who doesn't perceive her nerve signals as always pain, will help.