pencil in your mouth! [laughter] how do we eat good mood food? what are they? >> research shows that there are certain types of fats that are going to have an anti-depressant effectod fats in shrimp and salmon and snapper. other research shows that it's the bad fats actually, so trans fats or partially hydrogenated oil can make us feel more aggressive. they stimulate a real inflammatory response. dr. oz: i'm laughing because they're laughing. eat omega 3's, they're good for you. do you feel better after having the pencil in your mouth? [laughter] dr. oz: this is crazy. it's amazing. it's true, it really works. >> yeah, it does. it does. dr. oz: the fourth item. if you don't pencils in your mouth and smiling, without any question just to endorse it, it is so important to walk down the hall wherever you are at home or work and smile. people think you're crazy or they'll smile at you or with you. they're mirroring it back. this one shocked me. i had heard about smiling. i'm a big fan of mood foods and daylight which is important in the winter months. i didn't realize that yawning is so important. i would love it if you would explain to folks all of your discoveries