We all struggle because we're only human.
It's hard sticking to a plan. If you're tired or stressed or feel like you have too much on your plate already, sticking to a diet and exercise plan is just another chore. For me, it would be way easier just to eat what everyone else in my family is eating, but I have to go out of my way to not only cook food myself, but make sure that the fridge and pantry are stocked with things I want to eat. Some days I just don't feel like cooking, and my mom gets us all fast food, so I just give in and eat it. That might involve fitting it into the plan, or just blowing it altogether. But other days, things are easy. You have to look at both your successes and your struggles, so you don't get caught up in thinking about how hard this all is.
But you got back after three days, and you weren't doing horrible, like you said, you were doing okay. Three days of okay are better than three days of nothing.