A final word on my London trip, then I'm done — I swear.Among those at this conference I was attending, some big former CEOs and statesmen. People that I had covered years ago — in one person's case something like 20 years ago.It was that person, and I won't name names, who really struck a chord with me. In his day, he was "the" guy, "the" CEO, "the" mover and shaker. He's just shy of 80 now. But he seems a little sad now."You know what's the worst part of being retired," he asked me."What?" I said."Being retired," he joked.He missed the game. The challenge. The pressure. The race. He missed it all. It wasn't a money thing — he clearly has enough of that. Nor was it simply a power thing — although I think he missed some of that. No, it was a "where do I fit in now?" thing.And this former CEO was feeling very different from his former self.We chatted up our numerous conversations and interviews those many years ago, when he was at the center of it all.He remembered how one time I chased him down a series of escalators at a shareholders meeting, complete with my camera crew in toe."You were a challenge, Cavuto," he'd say. "But you know something... I loved every minute of it." Then, as if muttering to himself, he ended, "I miss it." His crinkled eyes looked around the room. They were sad eyes. Remembering happier times.It got me thinking — boy, things can change.We live so much in the moment that we fail to see the moment for what it is — just a moment.Life goes quickly. Fame quicker still. One moment we're the center of our universe. Then suddenly the center of no one's universe — save some family, some friends and a few souls who knew us when we had it all.And love us still when we don't.What do you think? Send your comments to: email@example.comWatch Neil Cavuto's Common Sense weekdays at 4 p.m. ET on Your World with Neil Cavuto.