How do you understand what Dad said to Lingling in the ninth paragraph of Lingling's painting?

Dad's last words are the feelings caused by Lingling's painting change and the central sentence of the text, which has profound educational significance. It has two meanings: first, the attitude towards things in life, we can't treat some things we didn't do well or accidentally did wrong as bad things, because good and bad can be changed; Second, when things go bad, we should not panic. We should calm down and use our brains to find ways to make up for it. Note that "bad things" here generally refer to unsatisfactory things, not bad things such as violating discipline and law.