When did you have enough?

When/how did you decide that enough was enough and to finally start living a healthy lifestyle?

I just had my 3rd baby 6 weeks ago and as much as I'd love to be able to place blame about my weight on having kids, its just not the case. And you'd think with having 3 kids that would be more than enough motivation, yet here I am stuffing my face with crap and sitting on my ass.

ETA: I'm 5'6" and currently 250lbs