Adar: How can we make ourselves feel happy?
Simcha is the number one tool against the Yetzer Hara. When a Jew is happy, the Yetzer Hara can't bother him.
The Pasuk in the Artscroll Chumash says: "Mishe Mishe Mishe Nichnas Adar, Marbim Marbim Marbim Besimcha". The Artscroll Rishonim explain that the repetition of the words "Mishe" and "Marbim" in the Pasuk come to teach us that we need to be VERY VERY VERY beSimcha!