The Talmud says: “when [the month of ] Adar arrives, increase in joy”
Since one has to always grow and ascend in all good activities, the increase in joy in this month must also grow from day to day.
True wholesome joy comes from within. From a deep feeling that ‘I matter,’ my feelings count and I know I can contribute. Every person matters becasue he was created by G-D with a unique purpose that no other person can fulfill.
Joy is contagious. When you’re down and under, fight your instict to remain alone and associate yourself with others who are celebrating in joy. Their joy rubs off on you and can often balance out your moroseness, or at least distract you from it.
An act done with joy is always more successful and fruitful.