Motivation Killer #1: Unrealistic Expectations
The most common cause of disappearing motivation is unrealistic expectations. When you have your hopes set on one thing (like seeing the number on the scale go down), but something else happens instead (the number doesn't change or it goes up), of course it's difficult to keep on doing what doesn't seem to be working for you. That's normal, and it's exactly how you're supposed to feel. These feelings help you avoid doing the same thing over and over again, expecting to get different results.
But this natural reaction becomes problematic when the result you're hoping for isn't likely to happen, like seeing predictable and consistent changes in your weight every week; or expecting to go from confirmed couch potato to exercise maven by sheer force of will, without paying your dues.
So, if your motivation is lagging because you're not getting the results you expect, check to see whether your expectations are realistic or not.
Here is what you SHOULD expect when it comes to weight loss:
Motivation Killer #2: Perfectionism
Weight loss is NOT orderly or predictable. Shedding pounds is only one of many healthy changes your body undergoes when you decrease your caloric intake and/or increase your activity level. A lower number on the scale may be the least important of these changes, even though it may seem to be the most important. Every body will respond differently. You may lose weight easily and quickly at first while your friend will have to wait weeks or months to lose that first couple of pounds. For others, weight loss may come in waves. All of this is perfectly normal.
Weight loss is NOT a simple calculation. Although we talk about weight loss in terms of numbers—calories in versus calories out—your body is not a calculator and it doesn't operate like a checking account. It is a complex, living organism with many needs and priorities to juggle, and difficulties to overcome (poor habits and thought patterns). A classic example of this complexity is how the stress you experience when your body doesn’t meet your weight loss expectations actually increases fat storage. There is a connection between your mind and your body. Instead of solely focusing on the scale, you need to take a comprehensive view of this process of change and work hard to keep your mind from getting in the way.
Focus on what you can actually control—what you eat and how much you exercise. You will lose weight if you do your part, and it will probably occur at the expected rate. (When you get to your goal and look back at the process, you probably will have lost at the rate of 1-2 pounds per week, on average.) That's what happened for me, over the 18 months it took me to lose 150 pounds. Those weeks where nothing changed, or I actually went backwards, drove me crazy and sapped my motivation until I finally realized I was focusing on the wrong things. When I started focusing on the small, positive changes I was making in my diet and in my capacity to exercise, life became easier and more rewarding. That, I believe, is our role in this process. The rest is not up to you, and trying to control what you can't control is a prescription for failure.