Thinking short term is normal. We resist long term goals and long term thinking because we know we will lose sight of the day to day dieting that is necessary to lose weight consistently. We try to give ourselves false goals like being able to lose weight by some future date or event such as an upcoming class reunion or wedding for example. And if the motivation is strong enough you will lose the weight. The question is: how will you keep it off after the event has passed?
We all hope and pray that we have become so accustomed to the diet and exercise routine that even after the event we will stay motivated to continue down the healthy path, but that is not usually the case. Most of the time we diet for the wrong reasons and after the momentary victory of being able to lose weight temporarily has passed and all the people slapping you on the back and giving you high fives have gone you still need to look yourself in the mirror each day and continue with the good fight.
And it is definitely okay to have a short term goal, just dont do it at the expense of the larger reasons to lose weight, like getting healthy and living longer. Being overweight can lead to very bad health problems like heart disease, diabetes, stroke, and hypertension. Not to mention all of the pain in the joints and problems with mobility that obesity can present to sufferers. The most important thing in your life is your health and you need to lose weight in order to give yourself that glowing health that will then give you a higher quality of life.