There's a well-known anecdote about a teacher who wanted to instill the concept of priorities in his students. Here's how the story goes:

One day, a teacher brought to his classroom a large glass container. He filled it with large rocks and asked his students if it was full. When the students answered in the affirmative, he started to add pebbles to fill in the spaces around the rocks. When he was done, he again asked the students if it was full. When the students replied yes again, the teacher added fine grains of sand to fill in every last crevice in the container. When the students were finally convinced the container was full, the teacher still found room to pour water inside.

"So," asked the teacher, "what have you learned today?"

One eager, young man jumped to his feet and said, "No matter how full your life is, there's always room for more."

"Thank you," said the teacher, "but that is not the point I was making. What I was trying to show was that you have to get the important things in life, the big rocks, in place first. Otherwise, you will never fit them in and all you'll be left with is sand and water."

Then he asked his students to consider what the "big rocks" in their lives were: G‑d, family, friends, health, ambitions, safety, being loved, loving others. The list ran on and varied according to each student.

(Check out a great article by Aron Moss, for a uniquely "Jewish" version and inspirational lesson of this story, by clicking here.)

With this little story in mind, I set out on the mundane task of filling one of my decorative glass vases with colorful potpourri–an assortment of ornamental balls, sticks, rectangles and spirals, all ranging in size.

Like the wise teacher instructed, I began with the largest balls. But to my dismay, once they were all firmly in place, I found the smaller items just couldn't fit. Worse, there were large gaps all along the periphery of my vase, on the bottom, at the sides, and in the crevices where the smaller pieces would have fit nicely had they been put there first, but now simply could no longer squeeze past their larger counterparts.

So I tried shaking the vase a little. That helped for a few very small pieces, but most were helplessly stuck in place.

That's when I realized that while the above lesson works well with a square box or a circular container, it fails in one that has curves. In this case, the lesson literally falls through the cracks. Each piece—big and small–needs to be intentionally put into its rightful place, and the significance of all the pieces becomes evident to form a more beautiful whole.

Real life is kind of like that, too. Sure, it's essential to focus on your priorities. But life is fluid and full of curves–changes, stages, and junctures. And as fast as you figure out the order of one phase, you're already onto the next. An inflexible list of goals or priorities that doesn't accommodate change leaves much lacking. And every once in a while, those "small" goals can sneak up on you, and prove to be just as important—if not more—than the big ones.

Take spirituality and connecting to G‑d. I would call that a real "big rock" in the grand scheme of things. But suppose you were in the middle of your daily talk with G‑d, enraptured in prayer, deep in meditation, when you're interrupted by a loud knock on the door. A little kid who just fell and got a bloody nose is standing there, pitiful, and he's asking for your help. (Hey, it could even be your own kid.) How do you react? "Sorry kid, I'm focusing on my 'big rock's'—one sec, this may even be the biggest rock that I'm putting into place. I'm being really s-p-i-r-i-t-u-a-l. Come back a little later when I'm back to earth."

Or take the ideal of being a selfless and generous person. That's another "big rock" that we're meant to devote a lot of time. But suppose, at this particular instance in your life, you've overextended yourself. Maybe, at this moment, the greatest favor that you can do for others is to take care of yourself. So, is nurturing your own needs a little rock or a real big one? Is replenishing your own energy selfish or selfless?

Small rocks or big ones? Pebbles or sand? It's not that simple.

We need to keep reevaluating at every new bend. And we can't become so inflexible that life's pieces become so stuck in place that they prevent others from fitting in and making a more beautiful whole.

Because, in real life, we don't live in a box.