It has been stated that an app running a HKWorkoutSession will have special privileges over other watchOS 2 apps, so when a user looks at their Apple Watch, it will go to the vi
We're seeing that too, for the moment we've made sure 'opens last activity' is configured.
When the UI is active we start a dispatch_timer to request and process data in 1 second intervals.
Make sure you do any significant processing using the NSUserProcessInfo method though and pause the dispatch_timers whenever you are no longer active. You'll get crashes otherwise.