The Importance of the Opportunity Cost

We seem to value things available to us immediately more than we value things that are available to us in the future. Give a real world example. Let's say you needed a pair of running shoes, right s you go to amazon dot com. You're still getting an 80 dollar pair of shoes in three years. But just like you would have to sacrifice three years of potential running days with your new shoes, these people have to sacrifice years of being able to buy something else by having that money in the bank.