"I'm going to begin some aerobic activity." "I'm going to start eating better." "I will talk to someone about weight loss." These are not specific goals! You have to clearly define what it is you are going to do. Our example of losing 25 pounds for a vacation is a rather large goal and should be broken down incrementally, ultimately leading you toward weight loss.
I would set a series of small goals to create multiple success opportunities. Here are some examples.
Goals like this can be accomplished on a weekly basis. When you find yourself repeatedly accomplishing them you experience increased motivation because of your success. This initial motivation builds upon itself and grows, allowing you to achieve goal after goal, ultimately leading to accomplishment of your vision-in our example, the loss of 25 pounds.