The chapter provides an insight into the role of design and sensory experiences in public health and ageing well through the lenses of playful design. It presents, through a number of relevant examples, the role of playfulness as a trigger for engaging people and especially older adults with physical exercise through tangible play. Emphasis is placed on the potential, benefits and challenges of designing playful sensory experiences and activities (interventions) for public health and ageing well. Following a review of the relevant literature on playfulness and sensory experiences and health, a number of projects that incorporate playfulness and sensory experiences are presented. This is followed by a presentation of the Active Parks case study. Active Parks co-created an interactive and playful walking trail that offers casual physical activity in one of Lancaster city's park. Working with the local community and a several key stakeholders a number of interactive and playful multisensory proof-of-concept prototypes were designed, developed and tested in the park. Based on the literature and the aforementioned case study a number of recommendations are provided on how to design playful sensory experiences for public health. This is the first paper of its kind to offer such practical recommendations that aim at public health and playfulness focusing on adults and older users. Keywords: playfulness, public health, ageing well; playful design, co-design, participatory design, interactive play, interaction design, design in healthcare. four key values and ten practical recommendations on the design of playful experiences for public health and ageing well in urban spaces. Related Work Playfulness There are several definitions of 'playfulness'. The most common ones widely accepted in the literature define 'playfulness' as a dispositional tendency to engage in play (Van Vleet and Feeney, 2015) or the predisposition to frame (or reframe) a situation in such a way as to provide oneself (and possibly others) with amusement, humour, and/or entertainment (Barnett, 2007). Play and being playful is how we first experience the world around us (Barnett, 1990), losing ourselves in play, whether it was creating a make-believe world, throwing a ball between classmates, teasing and role-playing with friends, etc. Unfortunately as we grow older we tend to distance ourselves from playfulness and get locked into the linear, problemsolution, adult mind-set. As Stanley Hall put it: "We do not quit playing because we grow old, we grow old because we quit playing" (Hall, 1904, pp 235). Although playfulness is traditionally associated with children, it is equally significant for adults. Van Vleet and Feeney (2015) identify in their review of the literature the importance of play behaviour and playfulness in adulthood and the need for more research in this area.