Now that he's home from the hospital, Reverend Billy Graham says he plans to write a book.

The book will be centered on the challenges and the joys of growing old.

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A Graham spokesman says the evangelist's faith remains strong and he is optimistic about the future.

The 89-year-old Graham was released from the hospital yesterday. Doctors had replaced a valve that drains excess fluid from his brain.

Before being discharged, it is reported Graham was taking short walks, keeping up with the news, enjoying notes from Christians around the world and visiting with his family.