Double tap to run

How do I make it so if a player double taps UP ARROW to run. Here’s what I got following a tutorial (this is only a portion of the whole thing):

    // toggle between walk and run with <left shift> R
    if(Input.GetKey(KeyCode.LeftShift) && Input.GetKeyDown(KeyCode.R))
        if(running == true){
            running = false;
            if(walking == true) Character.animation.CrossFade("walk");
            running = true;
            if(walking == true) Character.animation.CrossFade("run");

You probably want to record the time when the player presses the Up Arrow, and check it every time the up arrow is pressed. If the difference is less than a threshold, maybe 1 second, then toggle a variable (running = true;) and continue.

Of course, you’d also want to reset the variable (running = false;) after the up arrow is released to prime it for the next movement.

Hope this helps!