Wouldn't it be nice to have such a subject in school? They teach us how to read, write, count, sing and many other things, just not how to live. So how do we know how to live our lives?
We learn from our family, mostly from our parents. Our parents usually are no experts either, they are often struggling themselves. So how can they teach us something that they don't really know? Usually they don't, or at least not consciously.
It comes down to teaching us the do's and don'ts which are rather a tool of how to survive in our society than a list of advices about how to live a good life. If we do get some life advice, they do often more harm then good even if they are provided with the best of intentions. Do you recognize some of these: "Life is a struggle. More money more problems. People can't be trusted. Love hurts."?
Such saying are very dangerous because they get deep in our subconscious an are affecting our lives without us being aware of it. What are your negative beliefs? Write a list and replace them with something else - something positive. It can be for e.g.: "Life is a fairytale. More money more possibilities. etc."
Other important aspect is that children learn how to live not from what their parents say, but from what their parents actually do. In other words they see how their parents live their lives and learn from that. What have you learned from the life of your parents? What lives did they live? Were they satisfied in their relationships, in their work etc.?
The good news is that we can find those programs that do not really work for us and rewrite them if we want. Important is just our will to try it, our will to become a better versions of ourselves. We should be kind to ourselves on this journey, if we do not succeed in something we can just try again. What counts in the end is that we all the time do the best we can and that is enough.