Well, you need to look at it from holistic perspective, meaning look at how it affects all aspects of your life. Depression leads to a lot of things: problems with diet and exercise, smoking/drugs/alcohol, being around the wrong people, poor decisions, etc... It affects a lot more in your life than you know. It's like trying to pick a complicated lock. You can't just change 1 thing and expect to see it get better. You probably don't realize how much of your life has been affected by it if it's been this long.

My approach to dealing with this kind of stuff is to take a good solid inventory of your life and figure out what needs to change. Group it into 4 categories:

• Health - This means diet and exercise as well as smoking, drinking, drugs. Taking care of the body is critical for improvement.
  
• Social - Look at your social relationships. Are your friends the kind of people who make you a better person or are they just loyal and put up with you. Be around people that challenge you and make you better. Also, make more of an effort to do positive things with your friends. Things like going for a hike instead of sitting home and smoking and playing video games. Make an active effort to recruit new friends. Old friends are tough because of the loyalty but that doesn't always make them good for us.
  
• Stability - This is your ability to take care of yourself. This means your job, your home, your bills, your responsibility. It's not first on the list of things to change but it has to be an end-goal. When you are economically stabilized, there is less risk of falling into depression.
  
• Mind - Simply put, your thoughts. You need to develop a healthy mindset. That means knowing how to address depressive or obsessive thoughts. It means having a good outlook on life. It means having some kind of spiritual integration. (Doesn't have to be religion) Spirituality is how you cope with some of the tougher problems in life so it's critical. You can still be an atheist and be spiritual. Just means you have a system that works. You also need to start monitoring your emotions. Recognize emotional traps. Recognize ruminating thoughts. Recognize when your emotional response isn't proportional (don't cry over spilled milk) and lean how to address each emotional issue in a productive way.