The mundane level of right view teaches the principle of kamma

"The mundane level of right view teaches the principle of kamma: that we experience happiness and sorrow due to a combination of our past and present intentions. If we act with unskillful intentions — based on ill will, cruelty, resentment, or passion, either for ourselves or for others — we’re going to suffer. If we act with skillful intentions, we’ll experience happiness.

The fact that happiness and sorrow are dependent on present, and not just past, intentions is what allows the brahmavihāras to be effective in the first place. If everything depended on our past actions, we — and all other beings — would simply be passive victims or beneficiaries of forces over which we had no present control. But because our present intentions play a crucial role in determining whether we are to experience mental pleasure or pain now and into the future, the attitudes that influence our present intentions in a skillful direction can have a real effect in leading to happiness. The extent to which we can encourage others to develop similar attitudes will have a real effect on their happiness as well. Even when people have done unskillful things in the past, the quality of present skillful intentions and attitudes can mitigate those effects dramatically.

In this way, the teaching on kamma not only explains why the brahmavihāras can be effective means to happiness but also provides the reasons that motivate us to develop these attitudes: We need to strengthen them so that we can make our intentions more trustworthy.

At the same time, the teaching on kamma shows what it means to aim at genuine happiness. Because happiness has a cause — skillful action — your wish for happiness has to focus on the cause. Otherwise it will have no effect. This lesson applies to the sublime attitudes both when directed to yourself and when directed to others. Goodwill for yourself means being determined to act skillfully; goodwill for others means hoping that they will understand the causes for true happiness and act in line with that understanding. Compassion means compassion not only for people who are suffering, but also for people who are acting in ways that will create more suffering. Empathetic joy applies not only to people who are happy but also to people who are acting in ways that will lead to true happiness. Equanimity applies not only to sufferings that are beyond one’s control but also to actions that one cannot prevent.

All of this means that if you really want other people to be happy, you don’t just treat them nicely. You also want them to learn how to create the causes for happiness. The best way to do this is to show them through the example of your own behavior. If possible, you can also encourage them to follow your example. At the very least, you don’t thwart their attempts to act skillfully. This is how the brahmavihāras function in the context of mundane right view."

~ Thanissaro Bhikkhu "The Sublime Attitudes: A Study Guide on the Brahmavihāras"