Can I take part with just my phone?
Yes. On iPhone, choose Apple Health and your phone’s steps count. On Android, choose Health Connect; your phone’s step counter or a step app such as Samsung Health must write steps to Health Connect.
Counting starts by itself once you’ve connected. Carry your phone as much as you can, because it only counts steps while it’s with you.
Android: check that steps appear in Health Connect under Data and access → Activity → Steps. If no app is listed there, open your phone’s health app and let it write steps to Health Connect. If it can’t, install a step app that can.
For exercise-minute challenges, start and stop a workout in a phone app that saves to Apple Health or Health Connect.