How to deal with negative mood?

Find a source of good mood. Think about what makes you feel happy, what energizes you. Communication with children, going to the park, watching your favorite movie? You can even make a list of "100 things that make me feel good." Constantly replenish it and daily try to do something from what is written in it. The most important source of good mood is yourself. It is you who determines your state, and you can always change it. Take a break from work for 5 minutes, sit back and tune yourself to the desired wave.