Mood repairing strategies are used by us to shift our moods from sadness to content, and even to treat depression sometimes. These are basic acts applied to daily life which can improve negative emotions, and overall quality of life.
Mood repair strategies are also assigned by psychiatrists to their patients as homework, a means of cognitive, behavioral, and interpersonal tools.
When we are feeling low, we forget that things can be better too. A refreshing change or a sweet talk with family or friends can make a huge difference in our mood. There is nothing new about sadness or depression, but loving yourself always feels anew.
Just don't feed general sadness; that's what makes it grow into something more destructive like depression or dysphoria. A person's will and desire to change his perception and mood will be a key factor in his mood repair.
These techniques aren't very common yet, but they are thoroughly researched and approved by psychiatrists.