OK, my kids don't like me sometimes. There are times when they ask me for something they want. I tell them it is OK to get it, but they have to use their money to purchase it. As you can imagine, the tone changes and suddenly it is not as important as it was when they asked me to pay for it. When I ask them to pay the cost, they are forced to evaluate whether it is "worth it" or not.
I call this the value scales - is the cost worth what I am going to receive. Picture a scales - one side of the scales is labeled "COST"; the other side of the scale is labeled "PERCEIVED VALUE". We all have the value scales embedded in us - we are constantly evaluating whether what we are doing or buying is "worth it".
If something has no cost, then ANY value will tip the value scales toward the "PERCEIVED VALUE" side of the scale. I will always take something that has no cost but even a minimal perceived value. (Have you ever wondered why people always take free stuff that they just end up throwing away? There is no cost, so even if there is a very, very small value, the value scales tell me that it is worth it so I take it.) If something has a high cost, then we weigh the perceived value of it. If we don't think it will be "worth it", the value scales are tipped toward the "COST" side of the scale. We don't pursue it because we do not believe that the cost "outweighs" the value we will receive from it.
The value scales have large ramifications for our spiritual life. David expressed a part of it this way - I will not offer anything that costs me nothing (2 Sam 24:24). He understood that offering something that cost nothing indicated to God that it had little value to him. Paul said it this way in his letter to the Corinthians (2 Cor. 4;17) - our light and momentary troubles is working for us an eternal glory that outweighs them all. He looked at the value scales and said the cost that I am paying now with all the trials I am going through is "worth it" because I will receive some eternal reward that outweighs them. (Note that the only way one can make this statement is by looking at eternity through the eyes of faith.)
A teacher I listened to on the radio said it something like this - if we properly value the heavenly prize, we will sacrifice and endure now so that we will achieve later. We have to look at our behavior today in light of an eternal value scale. What costs we pay today, will provide worth in the future. If we don't believe that our current actions will have eternal consequences (good or bad), we will live like the man in Luke 12:19 who lived his life under the "eat, drink and be merry" philosophy. Consider this today - keep an eternal perspective in your value scales!
PS I have found that it is necessary to teach this scales to my children. If I continually indulge them without having them count the cost, I do them a disservice and train them to be self centered consumers instead of disciplined spenders.