Mindfulness improves well-being, improves emotional regulation, reduces impulses to eat, and is linked to increased physical activity. Mindfulness interventions usually focus on 1 aspect but do not offer an approach to holistically improving lifestyle. This study aims to address this gap by designing and evaluating a holistic mindfulness intervention. Committing to a 12-week intervention with 2-hour sessions without knowing whether you will enjoy it can be a hindrance for someone completely unfamiliar with mindfulness. For this reason, we decided to design a mindfulness intervention with short sessions over a reduced number of weeks. The aim is to enable novices to discover different aspects of mindfulness while at the same time offering a satisfactory practice for people who are already practicing mindfulness. We designed and evaluated a web-based mindfulness intervention in 5 sessions of 5 to 10 minutes each on well-being, diet, and physical activity to support a healthier lifestyle. The first 2 sessions focus on formal mindfulness meditation to enable novices to discover mindfulness and its main principles. Then there are 2 sessions about food. The first session about food aims to develop a sense of satisfaction with the food we eat and to focus our attention on new sensations. The second session about food aims to develop the ability to resist the lure of unhealthy foods. Finally, there is a session on physical activity. The aim is to develop a particular awareness of the body during movement, to increase satisfaction with physical activity, and to develop regular exercise. In total, 32 participants completed the intervention. After the intervention, we observed decreases in negative affect, anxiety, and emotional distress, and an increase in dispositional mindfulness. There was no effect on reported healthy eating habits and physical activity habits. Few participants repeated the exercises as recommended. The majority of our participants were new to mindfulness. The majority of our participants reported being satisfied with the different sessions. A few minor difficulties were mentioned, mainly related to the environment in which the participants carried out the sessions. Only 1 session was less satisfactory for one-third of the participants. The session on resistance to unhealthy foods was formulated too strictly and the idea of banning certain foods was a hindrance for one-third of the participants. A reformulation is needed. The mindfulness exercises were well accepted and promoted a state of mindfulness. It would be interesting to provide easier technical access to the exercises via a mobile app so that they can be repeated easily.