change the environment. feeling depressed is a state of mind. so its the best way that you change the topic at your mind. talk to your friends listen to your favorite music in short start something that you know lifts your mood.
you can try this yog exercise as well and let me know how does it work for you . its quite effective .
1. be attentive to your breath.
2. observe how deep you are inhaling. upto throat/ heart/ navel or deeper.
3. in most cases after this observation there will be a deep inhalation. automatic response of the body that want to change .
4. now try deeper and slower breathing .