Many spend so much time looking forward that they forget to look back to see how far they have come. Of course the mindfulness ideal is to live in the present moment at all times, but that’s a difficult task for most of us. Too many hopes and too many regrets.
But actually from a mindfulness point of view pondering the future or the past is completely fine and in fact encouraged as long as you are aware that you are pondering in the here and now. Projecting yourself forwards or backwards is a uniquely human ability, so why look unkindly upon it? As long as you remember that all of your life happens in the present tense the future and past can become good friends.