Building on the theory of planned behaviour (TPB), we develop a new model of purposive behaviour which suggests that desires are the proximal causes of intentions, and the traditional antecedents in the TPB work through desires. In addition, perceived consequences of goal achievement and goal failure are modelled as anticipated emotions, which also function as determinants of desires. The new model is tested in two studies: an investigation of bodyweight regulation by 108 Italians at the University of Rome and an investigation of effort expended in studying by 122 students at the University of Rome. Frequency and recency of past behaviour are controlled for in tests of hypotheses. The findings show that desires fully mediated the effects of attitudes, subjective norms, perceived behavioural control and anticipated emotions on intentions. Significantly greater amounts of variance are explained in intentions and behaviour by the new model in comparison to the TPB and variants of the TPB that include either anticipated emotions and/or past behaviour.