The Native American practice of smudging, or purifying a room with the smoke of sacred herbs, can help clear negative energy from a space and improve mood. Most people use Sage Sticks or Palo Santo Wood. When burned, sage and other herbs actually release negative ions, which research has linked to a more positive mood.
To begin, open a window or door. Prepare a clay or metal bowl containing white sand, or an abalone shell, ready for catching ash. Light the sticks by holding them in a flame for a few seconds, then gently blow out the flame, letting the material continue to smoulder. It is nice to use a candle for this if you like as the practice can feel more ceremonial. In traditional practice smudging would be used to cleanse the eyes, ears, heart, and emotions by surrounding yourself with the smoke.
Once you have cleansed yourself, traditionally you would leave the stick inside the bowl or shell allowing it to fill the room with smoke then dispose of the ashes respectfully by placing them on the earth outside. I prefer to drift the smoke into all the corners of the room to cleanse negative energy. The action of 'wafting' can be enough to distribute the smoke, but some people prefer to use a found feather. Then I extinguish the smouldering sage stick using the bowl.