Don't let whether you can "afford" something get in the way of you writing it down. Just take the time to really dream without limits and to be honest with yourself about what you really want.
This way you'll have a concrete goal to shoot for instead of saying: "I want to have the money to travel" or "I want financial security" or "I want a nice house and a nice car." These kinds of vague generalizations are nothing more than wishful thinking, and wishful thinking inspires passivity more than it inspires action.
Think about it this way: The more specific your target is, the better your chances are of hitting it. By quantifying the amount of money that you want, you'll engage your creative imagination and your internal sense of motivation will compel you to take action.
This is a form of self actualization. By writing down the things you want, you are implanting a seed in your mind about the relative worth to you of each of these things.
Conceptualization is always the first step in the process of Actualization - something your subconscious mind will move towards once you seed it with your conscious desires.
Just remember that as soon as you know how much money you need to have in order to get the things that you want from life, focus again on what you want. The more you do this, the greater your desire will become to achieve the end result, and the more motivated you will become to develop plans of action which will empower you to attract the wealth and prosperity you desire.