What is an example and explanations of practical advice for peace and inner-strength that are given in Bhagavad Gita?
One piece of advice given is that doing right is better than vowing not to do wrong.
In chapter 3, verse 8, there is an interesting piece of guidance for living a better life. If you live a proper spiritual life, you will be able to live a more moral life.
You should perform your prescribed Vedic activities since actions are better than renouncing actions; by ceasing activity even your bodily maintenance will not be possible. (bhagavad-gita.org)
This can be interpreted two ways. First, it is important to maintain a spiritual regiment. These activities make you who you are. Second, doing the right thing is more important than not doing the wrong thing. Also, doing the right thing is more important than condemning others who do wrong.