I left the shore.

See the stretching coastline far below the wing of the plane in the photo? Yes, I snapped the photo as we left land behind and soared miles and miles over nothing but water.

Leaving land was easy—much easier and faster than if I was on the ground. I knew the small line of white along the water was an expansive stretch of beautiful sand. I was sure there were many people on that sand, enjoying a beautiful day with a slightly different perspective than mine. I knew people on the ground were working, serving, struggling, doubting, celebrating. Lives were changing for good and for bad; some of it would be noticeable, and others would carry the changes inside for hours or days or years.

That stretch of sand, forming a line between the land and water, prompted me to consider the line in the sand. Most of us are familiar with the idiom. “The line in the sand” indicates a boundary that keeps someone within a commitment or marks the moment they step across it and go beyond where they planned to be or were told to stay.

There isn’t just one line in the sand for us. Sometimes it’s because we erase the line ourselves. We don’t like it anymore, because it no longer serves us. We want to go farther. We don’t value what we once did. We’re moving on. Other times, the line changes because we realize we need to consider the context and zig and zag the line as we grow and consider a different perspective. We expand the line in some places but retract it in others. We don’t entertain doubts or challenges aimlessly; we do so with intentional effort to learn, engage, and grow.

The lines we draw in the sand that we never plan to change will change over time any way. If we don’t pay attention to the line, the sand will blow, drift, or be trampled on. That’s the nature of sand. Our lines in the sand need to be attended to, and maybe that’s why we call them lines in the sand instead of lines in the concrete. We wouldn’t have to pay as much attention to those lines—and therefore, we couldn’t grow much—because they aren’t going anywhere.

The coastline below me that day seemed unchanging, but I’ve stood on the shore often enough to know the sand is always shifting.

Be mindful of your lines in the sand.