bite the bullet face up to doing something difficult or unpleasant; stoically avoid showing fear or distress.

☞ This phrase dates from the days before anaesthetics, when wounded soldiers were given a bullet or similar solid object to clench between their teeth when undergoing surgery.

2019Radio Times Patients include an anxious young man who, having avoided a vasectomy for a long time, has finally bitten the bullet and come in for the procedure.