Apple Watch Series 2 is reporting way too much exercise Twice in the last week my Apple Watch (Latest WatchOS 4) has reported massive amounts of exercise, when in fact I hadn't done any those days.  Like many hundreds of minutes of contiguous, non-stop workout.

I've rebooted both the watch and phone, and recalibrated my fitness data in the Watch app on the phone.  I've also deleted the two offending days' worth of data from the Health app, but the Activity app still shows the achievements for those "record" days.  So two questions:


Why is this happening/How can I prevent this from happening?
How can I remove the achievements so that I have a chance to actually earn them again in the future?
Turns out that this was being caused by a timer app I had installed, called "Intervals".  I'm not using it as a fitness timer, but it defaults to recording every use of the timer as exercise.  According to the developers of the app, there are individual settings within each timer to turn this off, but apparently those aren't quite enough. There is also a "low power" setting within the timer, that needs to be enabled to completely prevent fitness tracking within the app.