Add rotation to camera without contantly rotating it

im trying to rotate the camera by a certant number but its just moving it constantly.
Right now im going

runService.Heartbeat:Connect(function()
	cam.CFrame = cam.CFrame * CFrame.fromEulerAnglesXYZ(0,0.01,0)
end)

wich is just spinning it.
But i want it to rotate it by that number and have it stay rotated at that number.

Im using the roblox first person camera how would i do this?

So you only want it to rotate a certain amount of degrees? Why not use a for loop?

No its kind of hard to explain. I want to keep the normal camera rotation but add a certain amount to it every time with out it doubling up and spin. So like an offset? but for rotation

Consider this explanation from the Developer Hub

Then just multiply it without it being under a loop.

You’re modifying the camera’s CFrame inside an event loop RenderStepped which fires every frame. As has been suggested, move the code outside of the event in order for it to be executed once.