Objectives <p>The ability to focus on the present moment, also known as momentary focus, is recognized as a crucial psychological mechanism associated with state mindfulness and flow experience, potentially serving as a vital pathway to increasing current happiness. Motivation, an intrinsic or extrinsic drive to achieve goals, can influence our emotional state during momentary focus. However, awareness of motivation may be affected by individual differences in trait mindfulness, determining whether we are influenced by them. This study explored the moderating effects of motivation on momentary focus to predict happiness and examined whether individuals with high trait mindfulness were especially susceptible to the influence of motivations.</p> Method <p>We used the experience sampling method to capture the daily experiences of 56 Taiwanese college students over a 2-week span. Participants were required to report their current momentary focus, happiness, and motivation for engaging in activities three times a day.</p> Results <p>The findings demonstrated that momentary focus positively predicted happiness. However, higher external motivation weakened the positive association between momentary focus and happiness. Furthermore, individuals with high trait mindfulness were more sensitive to external motivation, which amplified the moderating effects of external motivation on the positive relationship between momentary focus and happiness.</p> Conclusions <p>These findings highlight the importance of minimizing the influence of external motivation in mindfulness training, particularly for individuals with high trait mindfulness.</p> Preregistration <p>This study was not preregistered.</p>