In 20 years of working with patients, I've found that people will commit to change only when their motivation outweighs the challenges. And a simple two-column balance sheet is a great way to measure your willingness to make the leap. Say you're thinking of losing weight: You might label the columns "Begin a Healthy Eating Plan" and "Continue My Same Diet," then list the pros and cons of each course of action (see below).
If the pros are dwarfed by the cons, you won't be able to stick to your resolution. But you can tip the balance. The first step is to accumulate more reasons to care; for instance, the person who wants to get thinner could learn more about the benefits of losing weight and eating right by talking to her doctor and reading up on the latest research.
Once you've completed a balance sheet that convinces you, hang it up on the fridge or even carry it with you; referring to it will help you through moments of weakness.
Now you need to make a plan based on your particular challenges. Here are six I've gathered from readers.