Stamina jump drain problem

Hey i am trying to make that when you jump you drain stamina but i ran into a problem.

if (playerController.m_Jump == true)
{
staminaSlider.value -= 3;

}

This works good but the thing is that if i spam the space button while im in air my stamina will get drained to 0.

So i need some help to fix that if you are jumping u wont be able to “jump” when already in air to drain stamina.

I am using the standard asset FPSController.

There should be an “onGround” variable, you might have to look for it though, then simply:
if isJumping and onGround then
…

I cant find that onGround variable in the Firstpersoncontroller script.