For me, it is all about forgetting the past AND using the numbers as data only. Numbers are not good, numbers are not bad, numbers are ... NUMBERS!
From there, I get to make the choice on what to do, how to do and when to do it ... well, kind of. When I see a 53, there's not much choice on what or when, or even how for that matter. The point is I am in charge of my life, not the numbers, not my doctors, etc, etc. IT'S MY LIFE (see Bon Jovi for more)!
Again, this is for me. For you it may be different, but here is another part of my thinking:
If I don't test (a lot!), change my sites, put a new cartridge in the pump, eat sensibly MOST of the the time, exercise, and all those other things a PWD does, then I GIVE UP CONTROL of ... MY LIFE. Just in case you missed it, IT'S MY LIFE!
Oh and here is a really important point - no one has perfect A1Cs, perfect BG readings, perfect diabetes regimens that fit into their lives, perfect anything. We are ALL struggling in some way to try and achieve the unattainable. You are no exception, so cut yourself some slack.
Start small. If you tested once yesterday, test 2 - 3 times tomorrow, 5 - 6 times the next day. If you ate crazy yesterday, eat a little less crazy today with something sensible added. Gain control a bit at a time, give yourself a high five every time you test regardless of the result, because now you have information on what to do.
One day, today. I know you can do it!