Problem getting my model to animate once mouse clicked

I have this script which lets me click the mouse and the player will go to wherever it is I have clicked. The problem I'm having is getting the player to animate so say I have a Ídle'and 'Walk' Animation, how would I get it to Animate when I click/hold the mouse key?

 var speed : int;
 
 private var targetPosition:Vector3;
  
 function Update () {
     if(Input.GetKey(KeyCode.Mouse0))
     {
         var playerPlane = new Plane(Vector3.up, transform.position );
         var ray = Camera.main.ScreenPointToRay (Input.mousePosition);
         var hitdist = 0.0;
         
         
  
         if (playerPlane.Raycast (ray, hitdist)) {
             
             var targetPoint = ray.GetPoint(hitdist);
             targetPosition = ray.GetPoint(hitdist);
             var targetRotation = Quaternion.LookRotation(targetPoint - transform.position);
             transform.rotation = targetRotation;
             
         }
     }
  
     transform.position = Vector3.Lerp (transform.position, targetPosition, Time.deltaTime * speed);
 }