I don't do it as a "mind trick," or some pitiful form of placation, frankly, it's more like trying to find the silver lining. I don't beat myself up over dietary or exercise trangressions, life's too short.
I'm probably a little older than you, when I was younger I spent way too much time finding too much fault with myself, and all that resulted in was my not truly appreciating what I had when I was at the top of my game, so to speak. Now, instead of saying "fat - stupid - lazy - no willpower - idiot," I realize, "whoops, overdid it" and move on. To focus on nothing BUT the overindulgence and find nothing but fault with myself and NO redeeming qualities in anything I've just done only compounds the situation. I would just beat myself up even worse.
I'm just saying that you have to do what works for you; I have to do what works for me. All Aandd asked for was words of motivation we have, which sort of almost falls into opinions, and since opinions are individual things, there is really no right or wrong (so lets leave it at that). A lifetime of health is just that, and it takes time and work. Constant unremitting striving towards inplacable perfection is a guaranteed path to misery. Put another way ... you have the potential of ending up with the perfect body, but you may never get a chance to take it out and have any fun with it.
Peace.