In this article, we present MARC, a model for assessing - and improving - the health of organisations from a humanistic point of view. It is a part of the quest for sustainability, currently a main theme in organisations. The components of MARC: Meaning, Authority, Rationality, and Care, are four aspects that are all needed, and need to be in balance in an organisation, to provide a work situation where people can sustainably thrive rather than be damaged and consumed for the sake of the organisation. Implications of the model are discussed. A conclusion is that trust is central to this healthy balance. This presents a real challenge for sustainability, as trust takes time to build - but can quickly be erased.