The rapid development of intelligent technologies has brought about significant advancements in healthcare for the elderly. However, in addition to the decline in physical functions, the elderly also face a range of issues such as social isolation, cognitive decline, and inadequate caregiving services. This paper aims to explore the adaptation of intelligent means in design to support the comprehensive well-being of the elderly. Based on the concept of impact-centered design and the emerging intelligent personal assistant (IPA) as the carrier, this paper proposes design tools and methodology that support the subjective well-being of the elderly. Then, the feasibility of the design methodology was validated through practical design, resulting in a monitoring smart ankle protector tailored for elderly social dancers “Gyro Dancer”. The research result indicates that the impact-centered design methodology effectively supports the creation of positive impacts, thereby achieving long-term well-being goals. It significantly enhances the ability of IPAs to improve the elderly subjective well-being. Additionally, the related design tools provide systematic and clear guidance for design practices.