Fairy Doors

On the shores of Lake Superior, I noticed something unusual in the woods near the cabin. There were wooden, painted fairy doors leaning on the base of three different trees. 

The working doors had hinges and a small door knob. I was intrigued. I went to each one and opened the door, but there was nothing behind any of the three doors. I was disappointed. 

I went into the cabin, found a piece of paper and a pen, and wrote out three short encouraging messages. I folded the paper in two, and placed one behind each fairy door so the next person to open the door will find a treasure.