Calendar milestones deserve our attention only when something happens. In my mind, the turn of the millennium was on January 1, 2000 because that was when we worried about Y2K problems. Nothing special happened on January 1, 2001.
A hundred years earlier, the only interesting thing about the change from the 1800s to the 1900s was the lack of a leap year in 1900.
And I don't want to hear from those who argue that we started with year 1, because we didn't. Nobody around in what we now call the year 1 (including the approximately 6 year old Jesus) called it year 1.
In this spirit, it's hard for me to think of my upcoming 60th birthday as any indicator of anything. The only event associated with this birthday already happened. When I turned 59 and a half, I became eligible to withdraw my IRA and 401k funds without additional tax penalty. I tried to figure out how to celebrate this last summer, but couldn't -- I certainly wasn't going to pull out the funds just because I could. I'll need that money later.