What you want depends on what you have; the cost is what you’re willing to give up.

What you want depends on what you have, and the price is what you're willing to give up.
The law of conservation of energy already explains that.

Self-awareness is the surest way to manage your own expectations. After thinking through the cost, most desires fade away on their own—like ordering food, glancing at the menu without forgetting the price list. Generally, once you've seen the prices, many dishes don't seem quite so tempting anymore.