Be responsible and focus your attention on your present kamma not worry about the past

"In another passage where the Buddha’s teaching kamma, he starts with the virtues of generosity and gratitude. For most of us, when we hear about kamma, there’s that “Oh darn” moment, where we start thinking about all the bad things we did in the past and all the bad things that are going to happen to us in the future because of that. But the Buddha doesn’t start with the bad things at all. He starts with the good. He does say that certain actions tend to lead to certain results, but the fact that a past bad action has happened doesn’t mean that you, acting in the future, can’t make some changes in how it’s going to be experienced.

He gives the analogy of a crystal of salt. You’ve got a crystal of salt, say, the size of your fist. If you put it into a cup of water, you can’t drink the water because the water is way too salty. But if you put it into a large, expansive river of clean water, you can still drink the water in the river. In the same way, if you develop an expansive mind, the results coming from past actions, even though they may be large crystals of salt, don’t necessarily mean you have to suffer.

So when the Buddha’s teaching kamma, it’s not primarily for the purpose of making you feel guilty or bad about what you’ve done in the past. He always emphasizes the fact that you have to realize you’ve made mistakes in the past, but you can resolve not to do them again. Then you develop an expansive mind: a mind of unlimited goodwill, unlimited compassion, unlimited empathetic joy, unlimited equanimity. A mind trained not to be overcome by pleasure or by pain. A mind developed in virtue and discernment. These qualities expand your mind, so that what comes in from the past doesn’t have to make you suffer.

What the Buddha does emphasize when he introduces the topic of kamma is the need to be responsible and to focus your attention on your present kamma, and not to worry about the past. Your focus on the present moment is not simply for the purpose of being fully present to everything in the present. It’s for the purpose of looking closely at the choices you’re making and the results they give rise to. What are you doing right now? What’s happening as a result?

When he was teaching kamma to his son, basically what he was teaching was how to be honest and how to be observant, so that his son would be a good enough person to learn the Dhamma to begin with. First, he reminds his son of the virtue of being truthful. That’s the honesty. Then he tells him what to be observant about, and how: “Look at your actions. When you plan to do something, what do you expect is going to come from that action? If you expect anything harmful, don’t do it. If you don’t foresee any harm, you can go ahead and do it.

“While you’re acting, if any harm comes up” — because, after all, some of your actions have immediate results; you don’t have to wait until the next lifetime. It’s like spitting into the wind. You don’t have to wait for the next lifetime for the spit to come back at you. “If any harmful results are coming up, stop what you’re doing. Don’t feel that you’re committed to continuing with the action. If you don’t see any harm, you can continue with what you’re doing. Then when you’re done, you look at the long-term results.” This is where the honesty has to come in, and the ability to be observant, seeing what you did and the results that came from what you did, and being truthful about it.

If you made a mistake, you go talk it over with someone else, someone who’s more advanced on the path, so that you can get some good ideas on how not to repeat the mistake. If you see no bad results, then take joy in the fact that you’re making progress on the path and try to continue with the progress, training day and night.

The Buddha’s teaching a lot of good qualities of character here. He’s teaching compassion: You don’t want to harm anybody. He’s teaching integrity, teaching the ability to take responsibility for your actions. He’s also encouraging a desire and a willingness to learn, and he’s showing you how to do it.

This is how you become honest. This is how you become even more observant. This is how you make good use of the teaching on kamma. Instead of getting upset about things you’ve done in the past, you say, “Look, I can focus on the present moment and that’ll make all the difference.” That way, you can learn from what you do in the present moment."

~ Thanissaro Bhikkhu "The Lessons of Good Kamma" (Meditations9)