The Bones that Walk by Joe R Lansdale
I had risked everything for this map, for this mine, and I knew that even though I was not exactly an old man at forty, this would be my last hurrah. When I was done, the money I had saved was gone. I had spent it on the mule and the supplies. After this, the best I could hope for was to go back to wrangling cows. Doing that at my age, looking at that probability of that for the rest of my life was another motivator. That and the fact that once upon a time I had been rich and had liked it. I wanted to like it again. But mostly, I wanted to find that mine. It always seemed to be just out of reach. Now, with my new interpretation of the map, I felt I was so close that all that remained was for me to dig it out and put it in a sack.