life-changing
life-defining

I could not see how life here would ever change.

Do not want to have children in the future, no matter how your life may change.

In 1914 however his life would change from business to war.

Life has changed for the big men of small countries.

But if we don't hear these stories, our lives will not change much.

So many lives have changed in the past three weeks.

"I wanted to bring you back to the place where my life changed."

Even when you first came back to visit in 1990, life for common people had not changed so much.

How his life had changed in a matter of minutes.

So she was thinking hard about the past five months and how her life had changed.