The National Weight Control Registry (NWCR) is an organization that monitors successful long term weight loss. They provide data they obtained from participants who had lost at least 30 pounds and kept it off for over 5 years. Here are some of the common practices that those successful in controlling their weight had in common.
98% Modified their food intake
94% Increased their physical activity
62% Watch less than 10 hours of TV per week
78% Eat breakfast every day
90% Averaged an hour of exercise per day
75% Weigh themselves once a week
These are some telling insights into long term weight loss. This shows that people with the most successful long term weight maintenance constantly monitor their weight and focus on proper nutrition and physical activity. Taking these precautions is not always an appealing route when society touts quick fixes with little effort. Weight maintenance is similar to real life, "there's no such thing as a free lunch."
There may be some people who have lost weight who didn't follow all of the above activities, but I still think those lifestyle changes can make a big difference for most people in the population. If you are attempting to lose weight, I'd encourage you to look at these 6 activities and consider which ones you could do better at.