Don't worry, it's impossible to behave yourself all the time. Just allow yourself the treats you've already eaten, forgive yourself for having broken your resolve for a short time, and then wind back up to your routine again. If you find yourself reaching for something you shouldn't, or putting off a bit of exercise, remind yourself you have a goal and put in that extra bit of effort to not eat naughty. Adding guilt and punishment will only reinforce any negative eating or emotional behaviours.
Also what you have to do depends on what sort of person you are. My workmate has a multitude of sweets in and around her desk, she can eat one a day and not want anymore. If I see them I want to eat them so I either have to go cold turkey and say no everytime she offers, admit I'm going to eat a few and let myself, or get rid of them (by eating them) so the temptation is gone. Problem with the last 2 options is that even if everything is gone she always brings more out and I end up eating more sugar than I think is good. So I find cold turkey works best for me with occasional treats or splurges when I am out of the routine of eating 'them'. You may be lucky to be a successful grazer and can just go back to whatever was your normal amount of treats.
And by the way, you still did your exercise, so you didn't fall off the wagon completely, you just had a 'pureness break' :happy2: