The answer can be learned from the following story which took place with Rav Avigdor Miller ??”?. In his older years he was told that he needed surgery to replace a valve in his heart. He refused to have the operation, insisting that he had bitachon that Hashem would heal him. His wife and family pressured him to undergo the operation but he steadfastly refused. This went on for a period of time, I don’t recall for how long. One day he suddenly announced that he would proceed with the procedure. When he was asked about his change of heart (pun intended) he said that as far as he was concerned nothing changed however he realized that he had no right to practice his bitachon on his wife’s cheshbon!
