Table 2.

Creating guiding principles.

Intervention design objectives	Key features
To help people to maintain their activity independently	Digital intervention to build autonomous motivation, self-regulation skills (eg, graded goal setting and self-monitoring) and confidence to become their own physical activity coach.
To help people maintain exercise in the long term	Focus on creating sustainable lifestyle physical activity habits rather than relying on supervised facility-based activities.
To reassure people with long-term health conditions that exercise is safe for them	Encouragement and reassurance for undertaking physical activity with long-term conditions provided in terms of condition-specific advice on consequences of activity, modeling examples of others with similar health conditions, links to local in-person support (including exercise referral scheme).