People have unlimited wants, but they can not satisfy all of these wants because of scarcity. People do not have unlimited time or money, so they must choose which options will maximize their overall happiness level.

For example, during the week, you can't go to work AND go on vacation because there are only so many hours in a day. Another example is that you may not be able to buy a home near your work and a vacation home because you have a limited amount of money.