question: During the COVID-19 outbreak, many people rose to the occasion by engaging in volunteerism and health work. We conducted two nationwide surveys in the United States (n = 2931) and China (n = 2793) assessing volunteers' and health workers' levels of mental distress and happiness. In spite of data being collected at different phases of the COVID-19 outbreak and across two different cultures, the results converged. Volunteers and health workers reported higher mental distress (e.g., depression, anxiety, somatization) than the comparison group. However, volunteers and health workers also reported more happiness than the comparison group. More importantly, in a follow-up in China (n = 1914) one month later, health workers still reported heightened happiness but were no longer more distressed than the comparison group. The changes in distress were partially mediated by happiness at the first time point, pointing to the potential role of happiness in coping with distress. In sum, the emotional landscape of volunteers and health workers was complicated-they experienced higher distress but also higher happiness than comparison groups. Future research would do well to include longer follow-up periods to examine how experiencing happiness during highly stressful situations predicts mental health over time. Supplementary Information: The online version of this article (doi:10.1007/s40167-021-00100-1) contains supplementary material, which is available to authorized users.