Finding internal peace can be a struggle and it has been a struggle for a very long time. In Surah Al An’am (6:81-82), Ibrahim (AS) said “Which of the two groups deserve peace more?” Allah says “They who believe and do not mix their belief with injustice those who have security, and they are (rightly) guided.”
In other words, when you do wrong to others, you are actually disturbing something within yourself. But Allah says those who do not wrong others deserve internal peace. There are many people these days that do things that are wrong and they do not find any internal peace. Many are on drugs to cope with the reality because they are disturbed inside themselves.
Imaan gives you calm, it gives you peace, you are not disturbed. You are not looking for a fix from something bad. You are at peace inside because of your faith and remembering Allah.