Humanity is facing existential challenges that require urgent action to address the triple planetary crises. Drawing on the principles of planetary health, the paper argues that health professionals and the health sector have historically been important drivers of societal change, and that time has come once again for the sector to take up such active roles in addressing the planetary-health challenges. The paper provides an overview of the current frontlines of planetary health in the Netherlands: in education, research, new governance and sustainable leadership, as well as in various movements for greater transformative connection and transdisciplinary collaboration. The paper concludes with a call to action: for health professionals to adopt a planetary health perspective, consider the impacts on health and the environment, and rearticulate commitment to social and intergenerational justice, and practically engage with the frontlines of planetary health to work towards a more resilient future.