It's been more than three months since she resigned as Britain's prime minister, but Margaret Thatcher says she hasn't quite adjusted to life out of politics.

"The telephone goes and immediately you think, `Oh, goodness me, the United Nations is sitting," Thatcher said during a television interview on "20-20" Friday. "And then you realize that it's no longer you anymore."Thatcher says she earned the nickname "Iron Lady."

"I think they are right. You have to have firmness in decisions," she said. "Frequently, the decisions you have to take are those which are right for the long term of your country and your beliefs, but in the short term, they're tough."