Resize Sprite at SpriteRenderer after set new Sprite to it

I need to change at runtime the Sprite from a SpriteRenderer and resize so it fits the previous Sprite size of the GameObject. My GameObject has two components: a Transform and a Sprite Renderer.

This is my code:
GameObject myGameObject = GameObject.Find("Background");
SpriteRenderer mySpriteRenderer = myGameObject.GetComponent<SpriteRenderer>();
Transform myTransform = myGameObject.GetComponent<Transform>();

Sprite myNewSprite = getSkinObject("spriteValue") as Sprite;
mySpriteRenderer.sprite = myNewSprite;
myTransform.gameObject.transform.localScale = new Vector3(0.7f, 0.7f, 0.7f);