Paying rent is a need
while buying a new video game is a want
  if you buy a new video game, you cannot pay your cell phone bill. this is an example
setting a long term goal
setting a short term goal
realizing opportunity cost

realizing opportunity cost

Explanation:

Opportunity cost is a dilemma where consumers need to choose what to do with their money. To buy something he or she wants, he or she necessarily needs to forgo other possible ways to spend their money. This is because consumers have a financial constraint, meaning they can't buy everything they want. Thus, the opportunity cost of buying a video game is all that one fails to buy with the money spent on buying the video game. For example, he or she could take a trip, buy an outfit etc. Thus every consumer choice involves an opportunity cost. In the narrated case, if he buys the video game, he will not have money to pay the phone bill. Being without a phone is very bad, so the opportunity cost in this case is high as it affects the welfare. Given this, the consumer will decide according to the usefulness of the video game and the mobile phone. Then he will choose to use the money for whatever brings him the most satisfaction and well-being.