Whatever its origin, a trigger event is invariably an “aha” moment that causes you to examine your life from a new perspective so that you gain new insight and see yourself as you really are. It’s arriving at a higher level of perception. You know that the course your life has been taking is no longer acceptable and that you need to change.

However, “The decision to lose weight, and the reasons behind the decision, do not necessarily differentiate the successful dieter from the unsuccessful dieter. In fact, the decision may only start the process but be insufficient to maintain enthusiasm beyond a few months,” says Kristi J. Ferguson, Ph.D., an associate professor at the University of Iowa Carver College of Medicine. So, what are some of the more common trigger events, and do they actually work to sustain weight loss?

Trigger: Medical Diagnosis

Examples: Cardiovascular disease, diabetes, hypertension, sleep apnea, low-back pain, fatigue.

How it works: You’re willing to change your long-standing, ingrained behaviors because you want to avoid their negative health consequences. You want to live longer, and you’re afraid your quality of life will be extremely low.

Will it last: Probably. A disturbing medical diagnosis or warning is the No. 1 trigger for long-term weight control. In fact, one study published in Preventive Medicine found that individuals whose weight loss was triggered by a medical event had greater initial weight losses and better long-term maintenance than individuals whose weight loss was triggered by any other life change. “Hearing that you have high blood pressure or that a close friend has just been diagnosed with diabetes can be an extremely powerful, teachable moment for making changes in your eating and exercise behaviors,” says Amy Gorin, Ph.D., assistant professor of psychiatry at Brown Medical School and the Miriam Hospital. However, old habits die hard.

Make it last: Don’t think that simply receiving a “death threat” will carry you to the gym every morning. This is a strong motivator, but you still need to come up with a strategy that will last forever. Also, keep in mind that a medical diagnosis can easily be tossed aside — “Well, I’m not going to live forever anyway.” Try to keep quality of life in mind: As long as you are alive, you want to live a good life.

Trigger: Special Event or Life Change

Examples: A wedding or divorce, a high school or college reunion, an anniversary, birthday, college graduation or a new job all can trigger a determination to lose weight.

How it works: You’re highly motivated, with a crystal-clear goal — you’ll do almost anything to reach your objective. But, oftentimes this means adopting behaviors that are probably only temporary.

Will it last: A special or life-changing event is a great motivator in the short run, and it can be used to help you get going. However, an overweight woman who wants to lose weight for her wedding day is unlikely to sustain her interest in weight loss beyond the wedding. “The process of weight loss is entered with some specific goal in mind. Once achieved, weight maintenance involves no goal-directed behavior other than ‘keeping at it.’ Maintenance, therefore, poses the major problem and requires a motivator that will keep people doing what they are unaccustomed to doing long after they have achieved their weight-loss goal,” says Ferguson.

Make it last: Use the special event as a kicking-off point, but plan in advance what you’re going to use as a motivator beyond the special event to maintain your weight loss. Keep in mind that this motivator needs to be equally as strong as the triggering event itself.

Trigger: Vanity

Examples: A terrible photo that makes you look heavier than you thought you were; running into an old friend who comments on your weight; seeing yourself in the mirror or on a video and not realizing that it’s you; not being able to fit into your “fat” pants.

How it works: Vanity can work in two ways. It can serve as a negative motivator, meaning that you will do whatever you can to move away from the negative stimulus. Or, the desire to look more attractive or be able to fit into different clothes can act as a positive motivator.

Will it last: Probably. According to Ferguson, attractiveness is one of the top motivators for successful dieters. But for it to be successful in the long run, the desire to be attractive must be more important than any distraction. It must be one of the more central themes in your life.

Make it last: It’s not a good idea to use that terrible photo just to get you pumped up so that you’ll have more willpower to resist tempting foods. Instead, use it as motivation to make a plan for how you will not only lose weight but keep it off permanently.

Trigger: Diet Pusher

Examples: A spouse, family member or friend pushes you to lose.

How it works: Your spouse, family or friends pester and nudge you to lose weight (and/or stop smoking or drinking), and you give it your best shot to get them off your back.

Will it last: Having the diet police looking over your shoulder at every minute can create resentment. If you lose weight for another person, you’ll probably start stuffing doughnuts down your throat the first time you get angry at that person. Whenever someone in my family told me not to eat something, I just took it as all the more reason to show my independence and shove that croissant down in two defiant bites. Then I felt doubly bad: guilty for eating the croissant and ashamed for disappointing both myself and my family.

Make it last: Sit down with your family members and have a reasoned, rational discussion. Make it clear that you know you have to lose weight, but you don’t want them watching all your food choices or telling you what you should or shouldn’t eat, because that will only annoy you and make it less likely that you’ll do what you already know you should be doing. Explain that they don’t have to modify their own lives, but they should at least support your objective.

Trigger: Competition or Success

Examples: Friends, family or co-workers decide to lose weight; a walking or weight-loss competition among your colleagues at work; seeing people you know succeeding at losing weight and keeping it off.

How it works: They make it look “doable.” If he/she can do it, so can I. Why not join in? It doesn’t look that hard. Or, you’re just plain competitive and want to win.

Will it last: There is a good chance the competition will last. For many, the determination to win at all costs begins the weight-loss process. And once the contest is over, they will likely continue on their weight-loss regimen because they’re pleased with their achievement. There is also strong motivation in seeing others succeed at losing weight.

Make it last: Seeing others succeed can be a great start, but make sure you use their example as the inspiration to create a plan of your own — not just to copy exactly what they did. For instance, just because your husband loses weight by following a glycemic index diet doesn’t mean that following the same diet will work for you. It’s the success you want to emulate, not the specific diet itself.

Trigger: Emotional

Examples: Overhearing a co-worker call you a fat slob; being charged for two seats on an airplane.

How it works: You’re embarrassed and use revenge as a motivator.

Will it last: Very possibly. Humiliation is long-lasting, and if you channel your energies into eating better and increasing your physical activity, you will likely lose weight and keep it off.

Make it last: Use this strong inspiration wisely. Don’t go to extremes. Set yourself up with eating and activity behaviors that are realistic for your current situation, especially in the beginning, while the memory of the humiliation is still fresh in your mind. For instance, don’t start exercising 90 minutes a day, seven days per week if you know that you probably will not keep it up. You’d be better served to start with a more realistic plan that does not require overhauling your entire lifestyle.