Send a Greeting Card to someone "just because" to let them know you are thinking of them.
With modern technology, this is almost a lost tradition of sending a card through the mail. People hardly send birthday cards or Christmas cards anymore. This makes this challenge a unique one because it will be totally out of the blue and a nice surprise for someone. You have to look for the "just because" cards but they are out there and it will be worth the time and effort you spend to find just the right card.
I absolutely love receiving "just because" cards because they truly show to me that someone cares because it is a lot harder and more work to send a card rather just email or text someone.