The goal of this clinical trial is to collaboratively develop and evaluate Active Ease, a co-designed, web-based digital physical activity application, to promote and maintain physical activity levels among individuals with severe mental illness in an Irish mental health residential care setting.

The main questions it aims to answer are:

• What are the barriers and facilitators individuals with severe mental illness face when participating in physical activity within an Irish mental health residential setting?
• What is the potential role of digital technologies in promoting and maintaining physical activity engagement for individuals with severe mental illness?
• Can a co-designed digital physical activity intervention, developed with HSE clinicians and service users, effectively promote and maintain physical activity levels among individuals with severe mental illness in an Irish mental health residential setting?

Researchers will compare two intervention houses receiving Active Ease to one control house receiving usual care.

Participants will:

• Engage with Active Ease across two consecutive intervention phases
• Wear a GENEActiv accelerometer for seven consecutive days at each data collection timepoint
• Have their body mass index recorded
• Participate in semi-structured interviews about their experience of Active Ease
• Complete a follow-up assessment at +12 weeks post-Phase Two