How do you stay motivated to exercise and diet?

 I've started dieting about a month ago and I was really committed to it; no cheating, exercising, drinking a lot of water, no alcohol. Everything went smoothly the first two weeks, but then I stopped losing weight.

Nothing really changed in my diet, I tried working out even more, but still not losing weight anymore, it's really frustrating and my motivation is slowly fading away. I get up on the scale after every meal, I weight myself in the morning, after exercising, before I go to bed, I'm literally obsessing over it and I realize it's not good for me. 

I am aware of the fact that at some point during dieting you reach a plateau and losing weight gets slower and slower, but still, I would expect at least a slight change.

If you could please tell me what I'm doing wrong and why I stopped losing weight, since I try to eat less calories that when I first started dieting. Maybe I should try a different diet? Also, has anyone heard of a quantum scale? It's supposed to be a scale that doesn't show you your weight, just records it and tells you your progress from the first day. Anyone used it? I'm thinking it would help me break this unhealthy habit of weighting myself 20 times/day. I'm starting to lose motivation to go on dieting because of it and it also irritates people around me.

Any kind of advice would be appreciated.