It DOES totally blow when that happens. It's freaking hard.

The only way I was able to get past that kind of disappointment (because sometimes it takes the same effort to lose 5lbs in a week as it does to plateau) was to focus on how I was going to maintain, what the day-to-day of the rest of my life was going to look like.
When I started coming to terms with the fact that I was going to have to count cals in some fashion, prep food, exercise, and sometimes pass up on things I wanted
forever to maintain a weight loss, it stopped being so much of a disappointment when the scale didn't move. That was defs not something I could accept overnight, but it gave me a lot of peace of mind when I could.
I started to feel good about keeping track and doing well with that instead of seeing the numbers go down. I also focused a lot more on exercise "victories." It sill sucked when I felt like I was doing everything I could and nothing seemed to changed, though! I just got better at not feeling gutted over it.