Given that I have no idea what the heck a Garmin Vivofit is....
I assume it's some kind of smart watch, that also mirrors all notifications from the "host" device.
If it's triggered by AquaMail "checking mail" or "push mail" notifications:
- Ask Garmin developers to exclude so called "ongoing" notifications from their mirroring. It's documented, it's official, I'm sure they can do it.
OR
- AquaMail settings -> look and feel -> status bar icon -> turn off
If you have old unread messages, and you get repeat notifications about them in the phone's status bar (and so on the smart watch too):
- AquaMail settings -> message notifications -> "notify about" -> change from "All unread messages" to "New unread messages".