The apps I have written talk to some pretty important things. For that reason I highly suggest that if you have a Samsung Watch that you turn on screen lock.
This feature locks your watch with a pin or pattern when you take the watch off your wrist or in the case of the newer watches after a period of time. If you are using Samsung Pay, this has the added bonus of not needing to ask for a pin or pattern a second time right before you make a payment since you already had to unlock your watch after putting it on your wrist.
This feature keeps your watch and the data on it safe without being too onerous.
You can find instructions on how to set this up here: