There are times when it seems old friends come out of the woodwork. Your paths cross for some mysterious, karmic reason, and it takes you back in time. Sometimes, it’s not an actual encounter at all–a glimpse of old photograph or a simple turn of phrase, and we become virtual time travelers. Instagram is full of the ubiquitous #TBT. (Does anyone even use hashtags anymore?) Facebook, too, incites rumination with its Year in Review and On This Date functionality. Whatever the trigger, rearview reflections are often useful in considering just how far we’ve come. Or maybe how much farther we’d like to go. At the beginning of 2015, I wrote three goals on my mirror. Run a marathon. Write a book.…