An iPhone counts steps. Apple's Exercise minutes, the green ring, are calculated on Apple Watch.
Steps can rise while the green ring stays still
Walk with only the phone in a pocket and the step count goes up. The green Exercise ring usually does not move. Those are two different records.
Where Exercise minutes come from
Exercise minutes come from the watch. It counts a minute when it recognizes a raised heart rate or a brisk walk. The phone's step counter is not that calculation.
Ordinary walking is not written as a workout
Unless an app explicitly writes a workout, the phone's own walking does not become Exercise minutes. The phone can keep a workout that an app saves. It does not turn an ordinary walk into one by itself.
What StepDay checks instead
StepDay uses Apple Health and the phone's motion sensor to judge whether today's walking counts as exercise. That answer does not need a watch. It writes this walk only when you start the guided interval walk: 3 minutes fast and 3 minutes easy, five times.
Common questions
Why do my steps go up when Exercise minutes do not?
The iPhone counts steps. Apple's Exercise minutes, the green ring, are calculated on Apple Watch. A phone-only walk usually moves the step count and leaves the ring still.
Can the phone's own walking become Exercise minutes?
Not by itself. Unless an app explicitly writes a workout, that walking does not become Exercise minutes. An app can save a workout onto the phone. Ordinary walking is not saved that way on its own.
Does StepDay need a watch to judge today's walk?
No. StepDay uses Apple Health and the phone's motion sensor. It writes this walk only when you start the interval walk.