caught in suspension

so you've heard people say time and time again to "live in the present."  Don't look back on the past and don't dwell on the future. But what does that really mean anyway? To me personally it is impossible not to look at the past. Isn't life about learning from our past mistakes and victories and living as a result of those implications? There is no way to change what has happened and you will never really forget.  It's kind of like when you say something inappropriate. You can't make it go away, you just have to deal with it and most likely it will affect your conversation.  Conversely, I can't just block out the question mark in my mind that represents the future.  What is the present? Is it the exact second, day, week, or era that you are in right now?  With no exact definition, it leads me to believe that there is indeed no such thing as the present.  Everything we do is the past at some point and also the future because it determines what will happen next. The only real way we could be in the "present" is if we could suspend the passage of time.  We cannot freeze time so we need to make the best of our lives which are made up of what we just did and what we are about to do.