Many people who perform paradigmatic examples of acts of supererogation claim that they could not have done otherwise. In this paper I will argue that these self-reports from moral exemplars present a challenge to the traditional view of supererogation as involving agential sacrifice. I will argue that the claims made by moral exemplars are plausibly understood as what Bernard Williams calls a ‘practical necessity’. I will then argue that this makes it implausible to view these acts as involving agential sacrifice.