Can you change the health regen of a character via a script which fires when I click the tool?

I'm asking if it's possible to change the health regen of a character with a script, If yes can you give me a link to wiki or something that relates to that?

Human = script.Parent.Parent.Character.Humanoid
while true do
	if Human.Health < Human.MaxHealth then
		Human.Health = Human.Health + 1
	end
	wait(1)
end

This will give him 1 extra health every second. To change the speed, change the number in the wait(1) to the speed you want to give him health. (1 = 1 second) Change the number in the Human.Health + 1 to change how much health he gains every time that happens. Put this script in StarterGui or StarterPack. Hope this helps :)