Physical activity (PA) can have a substantial benefit in the prevention, treatment andrehabilitation of (breast) cancer. Wearable devices offer possibilities to monitor PA,to provide feedback and to set targets. Although the market for PA related wearabledevices is booming, the impact of these wearables is questionable. One of the mainconcerns is the limitations to address individual needs of users, among which specificgroups such as women with breast cancer. Through design, we see opportunities tostimulate for self-enhancement while encouraging PA after cancer treatment.Following a constructive design research approach, Aymée was designed. Aymée is asmart bra that changes its pattern based on the amount of PA. Through thisinteraction, Aymée aims to reinforce women recovering from breast cancer to feelgood about themselves and to be (more) active. In this paper, we describe both thedesign approach in co-creation with former breast-cancer patients, as well as firstresults. We also discuss implications for designing intelligent systems that address PAencouragement.