You are right, we need to focus and control our present. But one thing need to be mentioned. You said forget about your past, it's perfect but not solemnly. I mean we must, need to remember the past in the mistakes perspective that what made our past dull. All these need to remember and design a chart of all the bugs of the past. Now in present situations, one needs to check out all those bugs drawn on chart either they are still waving or have been removed.
Below mention picture will probably illustrate my point more clearly

source-MyMistakes