Bad Day

I had a hard time with my eating today. I watched my three grandchildren, ages 7, 3 and 9 months all day and late into the evening. It seemed all I could do was keep up with them and I didn't have the time or energy to prepare myself healthy food. But it's just one day. The real question here is: do I let this one day turn into the beginning of a down hill slide? Or do I simply pick myself up, dust myself off, and start fresh in the morning?