local plr = game.Players.LocalPlayer --Player
local sprintSpeed = 30 --Configuration
local normalSpeed  =16
local function sprintCharacter(on) --Function makes it easier to control with just a boolean
    if plr.Character then
        if on then --If it's on, set the walkspeed to sprinting
            plr.Character.Humanoid.WalkSpeed = sprintSpeed
        else --If it's not, set the walkspeed to normal
            plr.Character.Humanoid.WalkSpeed = normalSpeed
        end
    end
end

game:GetService("UserInputService").InputBegan:connect(function(input, processed)
	if input.UserInputType == Enum.UserInputType.Gamepad1 then
		if input.KeyCode == Enum.KeyCode.ButtonL2 then --When the gamepad left trigger is pressed
			sprintCharacter(true) --Sprint
		end
	end
end)
game:GetService("UserInputService").InputEnded:connect(function(input, processed)
	if input.UserInputType == Enum.UserInputType.Gamepad1 then
		if input.KeyCode == Enum.KeyCode.ButtonL2 then --When the gamepad's left trigger is released
			sprintCharacter(false) --Stop sprinting
		end
	end
end)