Add value once when Trigger is pressed

I’m new to Unity and C# and currently playing around with character movements.
I want my character to run when pressing the right trigger of my xbox one controller.
I only have following problem: when pressing the right trigger, my running speed is added infinitely; when releasing the right trigger the running speed is subtracted infinitely.
How can I apply my running speed to my character only when the right trigger is pressed?
(Meaning as soon as I release the Trigger the speed is my ‘normal speed’).

This is the code:

if (Input.GetAxis("Run") == 1)
        {
            speed += running;
        }

if (Input.GetAxis("Run") == -1)
        {
            speed -= running;
        }

Its because you are constantly adding/subtracting the speed value whenever you use the triggers. Try making a variable that keeps the original speed then make speed equal that.

 public float speed;
    float origSpeed;
    
    start()
    {
    origSpeed = speed;
    }
    
    //then in your IF statement put this:
if (Input.GetAxis("Run") == 1)
         {
             speed = running + origSpeed;
         }
 
 if (Input.GetAxis("Run") == -1)
         {
             speed = running - origSpeed;
         }

I hope that helps