Self-efficacy is central to health behaviour theories due to its robust predictive capabilities. In this paper, we present and review evidence for a self-efficacy-as-motivation argument in which standard self-efficacy questionnaires - i.e., ratings of whether participants 'can do' the target behaviour - reflect motivation rather than perceived capability. The potential implication is that associations between self-efficacy ratings (particularly those that employ a 'can do' operationalisation) and health-related behaviours simply indicate that people are likely to do what they are motivated to do. There is some empirical evidence for the self-efficacy-as-motivation argument, with three studies demonstrating causal effects of outcome expectancy on subsequent self-efficacy ratings. Three additional studies show that - consistent with the self-efficacy-as-motivation argument - controlling for motivation by adding the phrase 'if you wanted to' to the end of self-efficacy items decreases associations between self-efficacy ratings and motivation. Likewise, a qualitative study using a thought-listing procedure demonstrates that self-efficacy ratings have motivational antecedents. The available evidence suggests that the self-efficacy-as-motivation argument is viable, although more research is needed. Meanwhile, we recommend that researchers look beyond self-efficacy to identify the many and diverse sources of motivation for health-related behaviours.