Make small short term goals.
I have not met a dieter that has made a goal that does not focus on this huge number of pounds to lose as a goal. We all have lofty goals, but we need to be both realistic and avoid goals that may be too lofty to accomplish. Although you might want to lose 100 pounds, you need to remember that you can really only average about 1-2 pounds a week and thus it may take you 1-2 years to lose 100 pounds. If you focus on a goal that may take your two years to meet realistically, you may become discouraged because you cannot readily see the light at the end of a tunnel that long. For this reason, I recommend a realistic short-term goal that can be fulfilled in 4-6 weeks.
Short term goals will give you a sense of accomplishment that can positively reinforce and build confidence toward your final goal. For example, you want to lose 20-30 pounds. Set an interim goal that is like 6-10 pounds in 6 weeks. Once you get to that goal, establish the next goal and focus on the next stage. Meeting this smaller goal will make you more confident and up your odds on success be because the more confident you are more likely you will meet this goal. As you build confidence, you will also gain more and more momentum toward your final goal. If you less successful than you planned at meeting the interim goal, look at your methods and refocus on the stage for your plan.
The bottom line: Smaller, short term goals build confidence and encourage you to continue. This type of approach will maximize success in building better health.