I like your analogy of the present being like a scale, having you to balance the past and future but stay in the present. It’s no easy task because our past some times has so much and even the slightest thought or action can trigger a past memory. Furthermore thinking ahead is also key in figuring out what to do moving forward.
Being present is certainly important, but it’s natural for us to drift back and forth to these particular times. What’s important is that we’re not in a constant state of dwelling on the past or thinking so far ahead we forget to live right now.