I am a bit sick of hearing: get over the past, don't live in the past, the past is the past, be in the moment, the present is all you have. I think what is really being said is “I am sick of listening to you” which can be very isolating. If we find it difficult to get over our past, there's usually a reason, and a good one at that.
Our past is our history. History can teach us a lot about people, nature, where we came from ... it's good and it's bad and everything in between, but being ashamed of our past is essentially the same as being ashamed of ourself.
Being in the present is important, it is where our power to change things lies, but not at the expense of forgetting our history. Forgetting, erasing or pretending our past doesn't exist doesn't feel healthy to me, integrating it and learning from it feels a lot better. Being at ease with our past is a sign of being at peace with who we are and where we have come from.
If you want to understand today, you have to search yesterday ~ Pearl Buck