In my life, when I am unhappy with work or the build up of stress and pressure in my everyday existence, I find that little emotional landmarks like spending time with Leo and Moira, long trail runs, visits to my hometown, and the familiar sights and sounds of Ann Arbor help me right the ship. Also, when faced with a tough decision, I try to base it on the long term goals Moira and I have set as a family. Those goals ground me and help me stay on course...they are landmarks. Staying on course is tough...both because you can lose your way or be tempted by the easy, well-trodden path (like a rail trail!). Moira and I are trying to take the road less traveled (like a mountain singletrack), but we have to remain vigilant to spot those little landmarks along the way.
So why a rock cairn? Well, a cairn is basically a broad name for a humble pile of stones. They are set is such a way that only a person could have erected them so. Consequently, when you are on the less traveled route in the woods or mountains, you see a cairn and know you are still going the right way. As a figurative symbol and as a literal landmark in trail networks I run, the cairn has become my own. I wear a cairn pendant from Tarma Designs around my neck always, to remind me to look carefully at the path before me and stay the course, no matter how challenging the trail ahead.
A little more on the cairn from Wikipedia:
Cairn is a term used mainly in the English-speaking world for a man-made pile of stones. It comes from the Irish: carn (plural cairn) or Scottish Gaelic: càrn (plural càirn). Cairns are found all over the world in uplands, on moorland, on mountaintops, near waterways and on sea cliffs, and also in barren desert and tundra areas. They vary in size from small stone markers to entire artificial hills, and in complexity from loose, conical rock piles to delicately balanced sculptures and elaborate feats of megalithic engineering. Cairns may be painted or otherwise decorated, e.g. for increased visibility or for religious reasons.
In modern times, cairns are often erected as landmarks, a use they have had since ancient times. Since prehistory, they have also been built assepulchral monuments, or used for defensive, hunting, ceremonial, astronomical and other purposes.
Today, cairns are built for many purposes. The most common use in North America and Northern Europe is to mark mountain bike and hiking trails and other cross-country trail blazing, especially in mountain regions at or above the tree line. For example, the extensive trail network maintained by the DNT, the Norwegian Trekking Association, extensively uses cairns in conjunction with T-painted rock faces to mark trails. Other examples of these can be seen in the lava fields of Volcanoes National Park in Hawaii to mark several hikes. Placed at regular intervals, a series of cairns can be used to indicate a path across stony or barren terrain, even across glaciers. Such cairns are often placed at junctions or in places where the trail direction is not obvious, and may also be used to indicate an obscured danger, such as a sudden drop, or a noteworthy point such as the summit of a mountain. Most trail cairns are small, a foot or less in height, but may be built taller so as to protrude through a layer of snow. Hikers passing by often add a stone, as a small bit of maintenance to counteract the erosive effects of severe weather. North American trail marks are sometimes called "ducks" or "duckies", because they sometimes have a "beak" pointing in the direction of the route. The expression "two rocks do not make a duck" reminds hikers that just one rock resting upon another could be the result of accident or nature rather than intentional trail marking.
Coastal cairns, or "sea marks", are also common in the northern latitudes, especially in the island-strewn waters of Scandinavia and eastern Canada. Often indicated on navigation charts, they may be painted white or lit as beacons for greater visibility offshore.
Modern cairns may also be erected for historical or memorial commemoration or simply for decorative or artistic reasons. One example is a series of many cairns marking British soldiers' mass graves at the site of the Battle of Isandlwana, South Africa. Another is the Matthew Flinders Cairn on the side of Arthur's Seat, a small mountain on the shores of Port Phillip Bay, Australia. A large cairn was built atop a hill next to the I-476 highway in Radnor, Pennsylvania, part of a series of large rock sculptures initiated in 1988 to symbolize the township's Welsh heritage and to beautify the visual imagery along the highway. Some are merely places where farmers have collected stones removed from a field. These can be seen in the Catskill Mountains, North America where there is a strong Scottish heritage, and may also represent places where livestock were lost. In locales exhibiting fantastic rock formations, such as the Grand Canyon, tourists often construct simple cairns in reverence of the larger counterparts. By contrast, cairns may have a strong aesthetic purpose, for example in the art of Andy Goldsworthy.