The problem is the diet, not you. :)
Dieting doesn't work; if it did, you'd be thin, and you wouldn't be here! Diets involve deprivation and denial, restrictions and shortchanging yourself. What you need is a lifestyle change. Embrace the Sparkpeople philosophy, and start making small, sustainable changes to everyday living. If you change your entire diet and start an aggressive exercise routine, you find that you burn out easily.
Sparkpeople has an article that really changed how I perceived weight loss. www.sparkpeople.com/resource/motivation_ar
I started my journey here by mixing my pasta half whole wheat, half regular, because I hated whole wheat and didn't like the texture, but could handle half a serving. From t here, I built up. Instead of having half a pizza, I had three pieces. Mixed my soda half diet and half regular until I liked the taste of diet. Started drinking more water.
And most importantly... I tracked my nutrition. Not guessing, but really weighing, measuring and tracking. Knowing what you're eating is the key to all of this. How do you know what small, sustainable changes to make unless you know exactly what you're eating? I've seen too many people here talk about "watching what they're eating" - you can still overeat, even on healthy stuff! Hummus isn't healthy if you consume an entire container in a day along with a bag of pita chips.