How to kill the player once the timer reaches a certain limit?

Hey there! I'm trying to figure out how to make the player have health on 0 (therefore, killing the player) once a timer reaches by, lets say, 10 minutes. I couldn't figure this out.

if mins >= 10 and seconds >= 0 then hum.Health = 0

This however doesn't work. Usually my time is around 0 to start. but the script sets the time to 10:00, Immediately killing the player once they spawn.

local mins = 9
local seconds = 40

repeat
    if seconds >= 10 then
        mins = mins + 1
        seconds = 0
    else
        seconds = seconds + 1
    end
    if seconds < 10 then
        script.Parent.Text = tostring(mins)..":0"..tostring(seconds)
    else
        script.Parent.Text = tostring(mins)..":"..tostring(seconds)
    end
    wait(1)
until mins >= 10 and seconds >= 0
if mins >= 10 and seconds >= 0 then
    local chr = game.Players.LocalPlayer.Character
    local hum = chr.Humanoid
    hum.Health = 0
end