At first, his secrets were just like everyone elses. He thought of them occasionally, and maybe felt embarrassed or wary, or perhaps they just brought back some old memories. But as he grew older, they started to accumulate, and he found it hard to avoid them. Like everyone, he felt the need to tell them. But he didn't want to cause the damage that telling them would create. So he bought a small plain notebook, and wrote them out, one a day, for catharsis. He enjoyed it. Just writing it out the way he wanted to tell it was enough for him, and he thought about each secret no longer, his clandestine mental stockpile dwindling with each day.
But whenever he had guests over, he couldn't relax. Every time one of them left the room, all he could think of was them stumbling across his book. He kept it in a locked drawer of his desk at first, then in a concealed safe. But that was not enough. Anyone going through his house would still definitely find it, and he couldn't bear to think of anyone reading his book. But he couldn't go without writing in it. He'd tried burning the pages, but it didn't work. He wanted to bury it far away, but then that would rob him of his release.
He keeps the book on his person at all times now. It's the only way to be sure no one else is reading it. But now he thinks of little else.