Achieving an ambitious goal frequently requires succeeding in a sequence of intermediate tasks, some being critical for the final outcome, and others not. However, individuals are not always able to provide a level of effort sufficient to guarantee success in all such intermediate tasks. The ability to manage effort throughout the sequence of tasks is therefore critical when resources are limited. In this paper we propose a criterion that defines the importance of a task and identifies how an individual should optimally allocate a limited stock of exhaustible efforts over tasks. We test this importance criterion in a laboratory experiment that reproduces the main features of a tennis match. We show that our importance criterion is able to predict the individuals’ performance and it outperforms the Morris importance criterion that defines the importance of a point in terms of its impact on the probability of achieving the final outcome. We also find no evidence of choking under pressure and stress, as proxied by electrophysiological measures.