AutoHotkey: Hold down key while true

Question

What it should do
z -> SetTimer, loop, -1
loop ->
IfWinActive -> press key
!IfWinActive -> release key

My Code:

#SingleInstance Force

z::
    SetTimer, loop, -1
return

loop:
    IfWinActive, Minecraft 1.8.9 | LabyMod 3.6.13
    {
        ; Press key aslong true
    }
return

But I simply not know how to simulate a key press aslong something is true

Edit:

Now I have this
It loops loop until i press z again

loop :=0

z::
    if (GetKeyState("w"))
    { ; turns the loop off if w is already pressed
        loop :=0
        SetTimer, loop, Off
        Send {w} ; send w again so you stop running why ever minecraft is like that
    }
    else
    {
        loop :=1
        SetTimer, loop, 1
    }
return

loop:
    while (loop)
    {
        IfWinActive, Minecraft 1.8.9 | LabyMod 3.6.13
        {
            Send % "{w Down}"
        }
        IfWinNotActive, Minecraft 1.8.9 | LabyMod 3.6.13
        {
            Send % "{w Up}"
        }
    }
return

But the problem is it constantly presses w up or w down if i wanny tab out the game it becomes buggy because i cant do a shortcut because it keeps interrupted by w down. it should only press w down until i tab out then it should press w up until i go in minecraft again

Answer 1

(tested) setting timer to -1 doesn't work for some reason replace (key) with the actual key to hold down

z::
    SetTimer, loop, 1
return

loop:
    IfWinActive, Minecraft 1.8.9 | LabyMod 3.6.13
    {
        send {(key) down}
    } else {
        send {(key) up}
    }

return

Answer 2

(fixed) i see your right you can't alt tab out of anything but you can make it stop when you press alt or tab like this. (also this is really useful i'm going to be using this in the future)

loop := 0
z::
    if (GetKeyState("w"))
    { ; turns the loop off if w is already pressed
        loop := 0
        SetTimer, loop, Off
        Send {w} ; send w again so you stop running why ever minecraft is like that
    }
    else
    {
        loop := 1
        SetTimer, loop, 1
    }
return

loop:
    while (loop)
    {
        IfWinActive, Minecraft 1.8.9 | LabyMod 3.6.13
        {
            if (GetKeyState("w")) Not {
            Send % "{w Down}"
            }
        }
        IfWinActive, Minecraft 1.8.9 | LabyMod 3.6.13
        {
            if (GetKeyState("w")) {
            Send % "{w Up}"
            }
        }
    }
return
!tab::
sleep, 100
send {d up}
send {alt down}
send {tab}
send {alt up}
return

you can change pressing down to this in to make it auto sprint!

{
            if (GetKeyState("w")) Not {
                sleep, 100
            Send % "{w Down}"
            sleep, 50
            Send % "{w Up}"
            sleep, 50
            Send % "{w Down}"
            }
        }