Dopamine is about expectation of intermittent reward

If we were designed by engineers, as we consumed more, we’d desire less. But our frequent human tragedy is that the more we consume, the hungrier we get. More and faster and stronger. What was an unexpected pleasure yesterday is what we feel entitled to today, and what won’t be enough tomorrow.

— Behave, Robert Sapolsky

Joy, pleasure, and satisfaction don’t stem from the achievement of something (unless it was unexpected). Instead, they happen primarily in anticipation of a reward, particularly if the reward is intermittent and you know the rules of the game.

You fast for 18 hours on an intermittent fasting diet. You know at the end of those 18 hours you get to eat! You have done this for a few weeks already and have become familiar with how this works and how you feel. Say, in a first scenario, you prepare your own food and so you know what you will eat, and it’s pretty much always the same meal with simple ingredients you have habituated to over time. The dopamine response (driving joy/pleasure) will be quite low, peaking in anticipation of the reward (the meal), and again raising when the reward happens (you eat). In a second scenario, you break the fast by eating a surprise meal prepared by your private chef. You don’t know the meal in advance, you only know that you’re hungry and that in the past the chef always cooked delicious and novel meals. Dopamine peaks very high in anticipation of the reward, and then peaks again a bit less once you’re delivered the meal and are eating it. After a few months of doing this every day, you habituate to the situation, and the dopamine peaks are globally lower.

This knowledge has practical implications in your life: you can introduce intermittent rewards as a way to incentivize certain behaviors for yourself and others, which eventually can change a whole system (your nervous system, your habits, your family dynamics, etc.). Dopamine is addictive (it is one of the main neurochemicals behind gambling for the same reasons discussed above, after all), and its manipulation can be incredibly effective, for good and bad.