, The first Exaflop-capable systems will be installed in the USA and China beginning in 2020. Europe intends to have its own machines starting in 2023. It is therefore very timely for computer centres, software providers, and application developers to prepare for the challenge of operating and efficiently using such Exascale systems. This paper summarises the activities that have been going on for years in the J¨ulich Supercomputing Centre (JSC) to prepare the scientists and users for the arrival of Exascale computing. The J¨ulich activities revolve around the concept of modular supercomputing. They include both computational and data manage- ment aspects, ranging from the deployment and operation of large-scale computing platforms ( e.g. the JUWELS Booster at JSC) and the federation of storage infrastructures (as for example the European data and compute platform Fenix), up to the education, training and support of application developers to exploit these future technologies.