Bit of a wobble this evening :-(

I've been really good for nearly 2 weeks now, I have had the odd tiny treat, not deprived myself but tonight I feel I've had a bit of a wobble and had a slice of homemade pizza after my tea, I wasn't even hungry. Just couldn't resist. Told myself the damage is done and try harder tomorrow, yet I did manage to add an extra 40 mins of housework in after I had this pizza to try and justify myself!
What do you do when you go off track a little??