you're going to have bad days (sometimes within your control because of your choices and sometimes out of your control because you're on vacation or get sick). Either way don't let those bad three days turn into a bad three weeks turn into a bad three years.
My journey has been losing 10-15 lbs over a 3-4 month span and then gaining 5-10 lbs back over the next 3-4 months. Those swings have narrowed as I got down to a healthy weight and i now stay within a 10 lbs range. My goal is consistency now.