Torso position isn't changing, how to check if player is within 5 studs of the NPC?

Below is a short code that I scripted. It gets the distance between the NPC's torso and the player torsos. If it is less than 5, it will print "We're within 5 studs." When I looked at the torso's position while I was walking, I noticed it wasn't changing, is there anything else besides position that I can use to check if the player is within 5 studs of the NPC?

This is in a local script in StarterPlayerScripts.

--Variables
local player = game:GetService("Players").LocalPlayer
local character = player.Character or player.CharacterAdded:wait()
local torso = character:WaitForChild("Torso")
local npc = game.Workspace.NPC or game.Workspace:WaitForChild("NPC")


function getDistance(distance1, distance2)
	local distance = (distance2 - distance1).magnitude
	print(distance)
	return distance
end

local distance = getDistance(torso.Position, npc.Torso.Position)

while wait(1) do
	print(distance)
	if distance <= 5 then
		print("We're within 5 studs.")
	end 
end

There is one obvious problem, and that is that you only check for the distance once, then use that. Instead, you need to check inside the loop, like this:

while wait(1) do
    local distance = getDistance(torso.Position, npc.Torso.Position)
    print(distance)
    if distance <= 5 then
        print("We're within 5 studs.")
    end 
end

You should also be careful, as if the player dies then you will need to reset the torso variable.

However, through experience I've run into an additional problem where the player's torso position does not change as expected. You could work around this by using the DistanceFromCharacter function of Player:

while wait(1) do
    local distance = player:DistanceFromCharacter(npc.Torso.Position)
    print(distance)
    if distance <= 5 then
        print("We're within 5 studs.")
    end 
end

While this only works with players, it's a lot simpler and isn't affected by the player dying (note that it measures distance from the head rather than torso, but the difference is negligable).