Access text object found in start() in another class function

I have created a class that I am calling from inside a non-MonoBehaviour and need to be able to edit text objects with. Finding the text object can only be done in start but obviously I am only running start once and am running my other functions a lot more. The problem is that due to the scope of timerText it cannot find a definition of timerText and I can't find it anywhere else. I don't know if there is a way to make timerText global or if there is a better way to find and change game objects in newly created classes but any help would be great thank you!

 public class MyMono : MonoBehaviour
 {
     public Text timerText;
 
     void Start()
     {
         timerText = GameObject.Find("Timer").GetComponent<UnityEngine.UI.Text>();
     }
 
     public void UpdateUI(string message)
     {
         Debug.Log("Received " + message);
         timerText.text = message;
     }
 }