With the increasing role played by software in supporting our society, its sustainability and environmental impact have become major factors in the development and operation of software-intensive systems. Myths and beliefs hide the real truth behind Green IT: IT is energy-inefficient because software is developed to make it so-intentionally or not. But how far are we from being able to control software energy-efficiency? What makes software greener? How can we transform measuring software energy consumption in a general practice? What architectural design decisions will result in more sustainable systems? How can we ensure that new-generation software will be both cloud-ready and environmental-friendly? and How can we make evident the economic and social impact of developing software with 'energy in mind'? These are a few of the challenges ahead for a more sustainable digital society. This talk will discuss them, hence drawing directions for exciting challenges, promising opportunities, and ultimately inspiring research.