During breaks when cycling or walking I paus the activity. The watch automatically stops and records the activity after a set amount of time, which is too short, especially if it is lunchtime. The watch vibrates before storing, albeit occasionally you may not notice.
Although the feature itself is fantastic, I believe it would be vital to provide the ability to combine more activities into one so that you may continue an activity even if you unintentionally save it or don't realize that it finishes automatically.