How to stop a countdown from counting down

Hi, please anyone can assist me finding out how to stop my counter from running when it reaches a certain number. In my case i would like to stop the counter and set another object Active. I looked around for answers but i am not able to find the answer. Here is the current script i have running the counter...Thank you and I really appreciate. var objectActive: GameObject; var timer : float;

function Start () { objectActive.SetActive(false);

}

function Update ()

{ timer += Time.deltaTime;

guiText.text = timer.ToString();

if( timer == 5){

 objectActive.SetActive(true);

}

}