Depression isn't just feeling sad/suicidal all the things (tired/lack of energy/abrupts changes in your social life) you describe can be symptoms. If you can't get yourself out of the rut it might be time to seek professional counseling. I would suggest trying regular exercise and eating right as a great start though. Just cut out fast food entirely, work in half an hour or so of working out every day or every other day. MOVE. Donate time at a homeless shelter or other charity.