Antonyms for the phrase "have cold feet" include being confident, certain, resolute, determined, and unwavering. Having cold feet refers to fear or uncertainty about a particular decision, action or event. On the other hand, being confident means having faith in oneself, abilities, and judgement. Certainty implies having no doubt or apprehension about a particular outcome. In contrast, determination is about having the will to succeed, despite the challenges. Finally, unwavering refers to being firm and steadfast in one's beliefs and convictions. Thus, when facing challenging situations, it is best to embody the antonyms of having cold feet to overcome fear and indecisiveness.