I've had several.
One that comes to mind was shopping at the plus sized store of the mall with my old best friend many years ago, and watching her pulling all sorts of things off the rack to try on. I needed a new pair of jeans, and as I sorted through the clothes I eventually realized that the biggest size they carried was far too small for me. Great. I was too fat for the fat chicks store.
I excused myself to one of the anchors to find a bathroom, hid for a while, and just bawled my eyes out. But at least I vowed to do something about it at that point.
While I'd lost quite a bit a weight after that, I was struggling in late 2011. Lots of personal issues, broken down car and no money to fix it, terminally ill family member . . . a lot of things took their toll on me and I stopped caring about watching what I was eating. And in the middle of it all, I found out I was pregnant, surprise! I was both excited and scared; I'd always wanted a baby but didn't have the energy to even think about it. How on earth was I going to pull it off? Then in early 2012, I miscarried.
I realized my weight had climbed up a good 25 pounds over the low point I'd struggled so hard to work toward and that I was on the road back to 300+. I made my mind up that I was going to take care of myself first and foremost, and knew that a healthier weight would follow. I also wanted so much to carry a healthy baby full-term, and have the energy to be a capable, active mother. I set a date to reboot my new lifestyle and began logging my food, the one thing that has always worked well for me. I haven't stopped since and wonder why I ever gave up on it.
And here I am at my lowest weight ever, four months pregnant.
I'd still like to lose another 60 or so pounds, but of course that will now have to wait until at least next year.
I think sometimes we need these points of realization, the defining moments to get us off our duffs; otherwise, what incentive do we have to change for the better?