I'm trying to make this sprint script use Left Control instead of sprint. Is this right?

I'm trying to make this sprint script use Left Control instead of sprint. But it doesn't work Is this right?

local p = game.Players.LocalPlayer
local c = p.Character
local m = p:GetMouse()

local sprint = false

local t,f = true,false

local w,a,s,d = f,f,f,f
local wt = 0

m.KeyDown:connect(function(key)
	if key == '50' then
		sprint = t
	end
	if key == 'w' then
		w = t
	end
	if key == 'a' then
		a = t
	end
	if key == 's' then
		s = t
	end
	if key == 'd' then
		d = t
	end
end)
m.KeyUp:connect(function(key)
	if key == '50' then
		sprint = f
	end
	if key == 'w' then
		w = f
	end
	if key == 'a' then
		a = f
	end
	if key == 's' then
		s = f
	end
	if key == 'd' then
		d = f
	end
end)

while wait() do
	wt = wt - .01
	if wt <= 0 then
		if script.Parent.Frame.Bar.Size.X.Scale < .9 then
			script.Parent.Frame.Bar.Size = script.Parent.Frame.Bar.Size + UDim2.new(.009,0,0,0)
		end
	end
	if w or a or s or d then
		if script.Parent.Frame.Bar.Size.X.Scale > 0 and sprint then
			script.Parent.Frame.Bar.Size = script.Parent.Frame.Bar.Size - UDim2.new(.009,0,0,0)
			c.Humanoid.WalkSpeed = 26
		end
	end
	if sprint then
		wt = 1.3
	end
	if not w and not a and not s and not d then c.Humanoid.WalkSpeed = 16 end
	if not sprint then c.Humanoid.WalkSpeed = 16 end
	if script.Parent.Frame.Bar.Size.X.Scale <= 0 then c.Humanoid.WalkSpeed = 16 end
end