A while ago my friend showed me the website www.gravityglue.com. It has pictures of some simply incredible stacks of rocks that this guy Michael Grab makes. Before you do anything else go check out the website. Go to the "My Work" link then "Stone Balance".
Prepare to have your mind BLOWN.
Since becoming enthralled with the website I've spent a little bit of time trying to make my own rock cairns out on the trail. Here are some I made recently.
So next time you're just not feeling it on your run........stop, grab some rocks, and get to work!