Individuals are not born with agency. It must be acquired and maintained. The process is one in which involuntary behavioural responses are transformed, through effort, into voluntary responses. These are then typically transformed, as a consequence of repetition, into automatic responses and thus themselves become involuntary. Any theory of agency must specify the limits to agency, whilst also recognising how easily it can be lost due to impulse, emotional intensity, or environmental stress. One limit is set by the inevitability of unintended consequences stemming from the collateral features of action itself. Thus, while paying attention might be thought to eliminate the unintended, the greater the attention payed to an action the greater the likelihood of unintended consequences stemming from that which is left unattended. Other limits on an individual’s power of agency stem from mannerisms, while habit effectively involves exchanging voluntarism for speed and efficiency. Another limit consists of natural behaviours that have been inhibited and hence cannot be performed ‘at will’, while there is also a class of desirable human states, such as sleep, spontaneity, and wisdom, that cannot be willed. Taken together the above add up to a considerable set of limits on willed action.