Despite recent popularity of mindfulness smartphone applications and an interest in incorporating mindfulness into new technologies, existing applications tend to focus mainly on its meditation dimension. In this paper, we review existing literature on digital and traditional mindfulness to map its design space and synthesize the findings with our prior research on designing for aesthetic needs. We identify "recollection" and "evaluation" as two important dimensions of mindfulness that have not yet been incorporated into popular digital tools. Through a two-phase design activity over 16 months, we developed ColorAway, an innovative tool that promotes mindfulness through interaction with modified travel photos. Recruited participants evaluated ColorAway and offered unique insights into how mindfulness can be better designed. We also discuss how the process of designing for mindfulness can possibly inform the design of personal technology. This research is part of a larger study that builds on scholarly research and theories with the goal of designing interactive technologies for solo travelers.