Money in the present is worth more than money received in the future, according to the time value of money. It is better to receive the $8 today because of unseen variables like inflation and interest rates. The $9 will not buy the same value of goods as it would have been seven years ago, so it is better to take the $8 today and use it. When planning to retire, it is important to consider investing the money to earn more interest. The time value of money encourages one to use the money at present, but when it comes to retiring, it is better to save the money and watch it grow over time.