Research shows that asking people to plan when, where and how to perform behaviour (i.e. implementation intentions) enhances the probability of action. Such implementation intentions can be formed alone or with another person. This study includes the data from two experiments which tested whether the effects of these different plans can be maintained for 6 months for physical activity and dietary fat reduction. Participants were divided into four groups based on how they would perform/avoid the behaviour. Participants would either:plan when, where, and how they would perform/avoid the behaviour with another person (collaborative implementation intentions)form similar plans on their own (individual implementation intentions) be involved with another person to help perform/avoid the behaviours (partner-based intervention) received no instructions (control) Participants in each condition completed similar questionnaires at baseline (time 1), one month (time 2), three months (time 3) and six months (time 4). Further information is available on the ESRC Award web page. The study looks at implementation intentions, goal intentions, and attitudes and beliefs around two areas: reducing saturated fatsincreasing physical activity