I do this periodically. I usually start with how many hours I think I'll work this week, then how much $ that will come to. Then, how much after tax, and how much each week if I work the same, and how much per month and per year. Then I deduct rent, and think about what I eat and how much each item costs and what that'll be weekly, monthly. Next is student loans, discretionary spending, think about necessities, toothpaste, soap, toilet paper whatever. It goes on and on, how much to save to go back to school, (classes, textbooks, bus fare) save for a car etc.,etc.
This is all done on paper by the way and I fill at least a whole page front and back with furiously scribbled multiplications. It also usually brings me to the conclusion that I need to make more money. But...
Then I think what if I get that raise, a quarter? 50 cents? a dollar?! !! I'll make this much more per shift, thats this much per week, month etc! I'll be rich!! I'll be sitting on a yacht in the Caribbean shouting "BUY!, SELL!" into a cell phone. LOL 