Dementia is a disease characterized by cognitive impairment and physical decline that worsens over time. Exercise is one lifestyle factor that has been identified as a potential means of reducing or delaying progression of the symptoms of dementia, maximizing function and independence. The purpose of this study was to explore physical therapists' (PTs) experiences and reflections on facilitating high-intensity functional exercise with older people living with dementia, in residential care home settings. The study used a qualitative design based on interviews, individually or in small groups, with seven PTs engaged as leaders in the training of older people with dementia. The interviews were analyzed with a modified Grounded Theory method with focus on constant comparisons. To increase trustworthiness the study used triangulation within investigators and member checking. The core category "Discover and act in the moment-learn over time" reflects how the PTs continuously developed their own learning in an iterative process. They built on previous knowledge to communicate with residents and staff and to tailor the high intensity training in relation to each individual at that time point. The category "Be on your toes" highlights how the PTs searched for sufficient information about each individual, before and during training, by eliciting the person's current status from staff and by interpreting the person's body language. The category "Build a bond with a palette of strategies" describes the importance of confirmation to build up trust and the use of group members and the room to create an interplay between exercise and social interaction. These findings highlight the continuous iterative process of building on existing knowledge, sharing and reflecting, being alert to any alterations needed for individuals that day, communication skills (both with residents and staff) and building a relationship and trust with residents in the effective delivery of high intensity functional exercise to older people living with dementia in care settings.