Abstract
The current global mental health crisis needs action. Here we show, using empirical evidence of randomised controlled trials combined with Rose's theoretical framework of preventive medicine and epidemiological principles, that the universal practice of kindness is a potentially effective grassroots public health promotion action that could propagate from the individual to the collective. Beyond effectiveness alone, we present medical ethics principles to show that the universal practice of kindness is also relatively costless, socially just, inherently consensual, empowering, and immediately available to, for and within every one of us. We argue that the need for structural changes and future research studies should not justify delaying the individual practice of kindness in our daily lives, since kindness is compatible with research, clinical practice and policy-making.