Scales
It seems to me that it is all too easy to become obsessed with what the scales says. I have seen blogs where people weigh themselves 3 times a day and lament that they gained back the two pounds at dinner time that they had lost by lunch time after their morning workout.
It takes time to gain weight and it takes time to lose it. The hourly and daily random ups and downs in weight completely swamp the slow and steady loss from dieting. Either decide to weigh yourself at wide enough intervals (like once a week) so that the overall trend can seen. Or if you can hack the math, weigh yourself once per day and then ignore daily figures and just look at an average of the last weeks data. The averaged data will show the true trend of weight gain or loss.
Use an accurate scales, there is nothing worse than adding more noise and uncertainty using poor equipment. After the first few days of this I purchased a Tanita HD 313-W Digital Bathroom Scale for $24 on Amazon. It has worked great.
Even when you're an engineer and you understand moving averages and even the exponentially smoothed moving averages that you are using to track the trend of your weight loss, it is still easy to get a bit disheartened by the daily weigh-in when it seems like the number is just stuck day after day. Have faith, just keep going and the number will inevitably drop.