Parshas Chayei Sara - How were Sara years all good?

How was Sarah able to consider her life a good life? She faced so many challenges and hardships? 

The Chovos HaLevavos writes in the Shaar HaBitochon that the essence of Bitochon is the peace of mind experienced by the one who possesses it. The people who know and feel that Hashem is in full control of every situation and always doing what's best for us will always be calm. 

Rabbi Sacks writes 

"Abraham and Sarah…survived whatever fate threw at them, however much it seemed to derail their mission, and despite everything, they found serenity at the end of their lives. They knew that what makes a life satisfying is not external but internal, a sense of purpose, mission, being called, summoned, of starting something that would be continued by those who came after them, of bringing something new into the world by the way they lived their lives. What mattered was the inside, not the outside; their faith, not their often-troubled circumstances."

Thus, the Torah tells us, ואברהם זקן בא בימים וה' ברך את אברהם בכל .In Avraham's old age, he looked back and

understood that every stage of his life was good. This was Avraham's way, to recognize that everything is a blessing.