To combat the public health crisis of Covid-19, governments and public health officials have been asking individuals to substantially change their behaviours for prolonged periods of time. Are happier people more willing to comply with such measures? Using independent, large-scale surveys covering about 79,000 adult respondents across 29 countries, including longitudinal data from the UK, we find that life satisfaction predicts compliance with preventive health behaviours during Covid-19 lockdowns, especially the number of weekdays stood at home (β = 0.02,p< 0.01). The association is stronger for higher levels of life satisfaction (e.g. β = 0.19,p< 0.01, 7 on a 0-to-10 scale). Lower life satisfaction, on the contrary, predicts lower compliance (e.g. β = 0.02,p> 0.10, 2 on a 0-to-10 scale). We explore risk-avoidance and pro-social motivations for this relationship, and find suggestive evidence that people who are older or have certain medical preconditions seem to be behave in line with risk-avoidance, whereas motivations of people who are less at risk of Covid-19 seem more mixed. While it is difficult to estimate the relationship between life satisfaction and compliance behaviour due to potential confounders and unobserved heterogeneity, our findings suggest that life satisfaction is important, both for complying with preventive health measures and as a policy end in itself.