Dale Breckenridge Carnegie was an American writer and lecturer and the developer of famous courses in self-improvement, salesmanship, corporate training, public speaking and interpersonal skills. Born in poverty on a farm in Missouri, he was the author of How to Win Friends and Influence People, first published in 1936, a massive bestseller that remains popular today. He also wrote a biography of Abraham Lincoln, titled Lincoln the Unknown, and several other books.
One of the core ideas in his books is that it is possible to change other people's behavior by changing one's reaction to them.
Inaction breeds doubt and fear. Action breeds confidence and courage. If you want to conquer fear, do not sit home and think about it. Go out and get busy.
You can make more friends in two months by becoming interested in other people than you can in two years by trying to get other people interested in you.