There are certain moments in life when we remember exactly where we were.

September 11, 2001, is one of those moments for me.

My wife and I had just finished about a 10-day vacation in New Orleans with two good friends. It had been a great trip. We had enjoyed the city and our time together, and that morning we were at the airport preparing to fly home to California.

We were literally standing near the jetway, getting ready to board our flight, when everything changed.

There was a television monitor near the gate. I remember seeing the first plane strike one of the World Trade Center towers - almost certainly a replay by the time we saw it - and then, within what seemed like a very short period of time, watching the second plane hit the other tower.

I also remember everyone around us just stopping. People throughout the gate area were glued to that television. We were frozen, trying to comprehend what we were watching. There was this collective sense of, “Oh my God. Is this really happening?”

At first, it didn't seem real. It looked like something from a movie. But after seeing that second plane, there was no mistaking that something horrific was happening.

What we didn't know was almost everything else.

Who had done this? Why? How could something like this happen? Were there more attacks coming? What else was happening that we didn't yet know about?

Today, we know the chronology of September 11. We know what happened in New York, at the Pentagon and aboard Flight 93. We know the terrible human cost. But standing in that airport that morning, we didn't know how the story ended.

We were watching it happen.

Within minutes, everything at the airport changed. Boarding stopped. Our flight was canceled. Eventually, air travel across the country came to a halt.

Our immediate thought was getting home.

We had young children in California and had already been away for more than a week. We started looking for another way back. Rental car? Nothing. Train? Nothing. Any other way of getting from New Orleans to California? Nothing.

There simply wasn't a way home.

So we remained in New Orleans for several more days. The change in the city was striking. We had just spent ten days experiencing a vibrant New Orleans filled with people, noise, music and activity. Almost overnight, it became quiet and subdued. With airplanes grounded and tourists no longer arriving, there was an eeriness to the city that was difficult to describe - almost apocalyptic.

Like much of America, we spent those days glued to CNN, trying to understand what had happened. Who had done this? Why? How could it happen? Were there more attacks coming?

There were far more questions than answers.

Eventually, flights resumed, and we were on the first flight out of New Orleans.

And we made it home to our children.

Twenty-five years later, I recognize how fortunate we were to be able to say that.

Nearly 3,000 people didn't make it home on September 11.

Husbands and wives, mothers and fathers, sons and daughters, friends and colleagues left home that morning and never returned. First responders ran toward unimaginable danger while others desperately tried to escape it. Families waited for phone calls that never came. Others received calls they would remember for the rest of their lives.

For us, September 11 was a frightening and surreal interruption to our lives. After several days, we were able to get on an airplane, go home, hug our children and eventually return to our lives.

For thousands of other families, there was no returning to the life they had known on September 10.

That distinction matters.

Looking back 25 years later, there is something else about that experience that stays with me: how quickly everything we thought was going to happen simply didn't.

We all make plans. We have to. But planning is not about predicting what will happen.

We can't.

On September 10, millions of people had plans for the following day. There were flights to catch, meetings to attend, children to pick up, dinners to have and ordinary lives to live.

Then the world changed.

Maybe that is part of why this memory resonates with me differently today after spending so many years helping people plan for their financial futures. A good plan doesn't give us control over what happens. It gives us a framework for making decisions when circumstances change.

I've often said that a financial plan isn't a document. It's an understanding of where you are, what matters to you, where you're trying to go, and the choices available to you along the way.

Markets change. Careers change. Health changes. Families change. Life changes in ways both ordinary and profound.

We prepare for what we reasonably can. And when something happens that we could never have predicted, we adapt while trying not to lose sight of what matters most.

For us, on that morning in New Orleans, the itinerary quickly became meaningless. The flight we were supposed to take didn't matter. How we got home didn't matter.

Getting home to our children did.

And maybe that's the enduring value of a plan. Not that life will unfold according to it. It won't. The value is knowing what matters most and having a framework for making decisions when circumstances change.

But September 11 is about something much bigger than any lesson I carried away from it.

It is a day to remember the nearly 3,000 people who lost their lives, the first responders and ordinary people who risked their lives trying to save others, and the families whose lives were forever changed by what happened that day.

Twenty-five years later, they deserve to be remembered.