Summarize:

Sometimes depression can be related to medical issues, including hyperthyroidism, Parkinson's disease, or Huntington's disease. It may also be a side effect of medication. If the depression isn’t caused by your medical condition, your condition may still affect your mood if you are feeling ill and thinking negatively. It is difficult to be positive when you are in pain or physically ill.  Meet with your doctor regularly if you have chronic medical issues. If you notice an increase in depression coincides with a new medication or other medical treatment, consult your doctor. Take all of your prescribed medication for medical concerns. It may take a while to find the right one for you. When you start feeling better, keep taking your medication as this may help maintain your health. With depression it may be difficult to keep up with daily tasks such as bathing, cleaning, and general self-maintenance (i.e. washing your face or brushing your teeth). Once you have successfully overcome the depression you can begin to get back your basic routine. Taking care of yourself can help you feel better about yourself overall and reduce the likelihood that the depression returns. For example, when you stay in your pajamas all day, it’s unlikely that you'll feel like leaving the house and doing something. However, if you take a long shower or bath, take care of your hair and makeup, pick out clothes you feel good in, you may feel much stronger and able to cope with the day. Make a list of things you can do for self-maintenance. This list might include: washing clothes, shopping for new clothes, washing your hair, getting a hair-cut or style. Exercise can help prevent and reduce symptoms of depression. As difficult as it is to put those sneakers on and tie the laces, after you have worked out you may feel ten times better both emotionally due to endorphins that are released in your brain.  Start off with a ten minute walk, and build up to 20. Doing that as often as possible may do wonders for you. If you have trouble getting up the motivation to exercise, try telling yourself, "I'll feel better when it’s done." Or commit to just doing five to ten minutes on an exercise bike or treadmill. Sometimes you just need to get over the initial challenge of getting up and moving, and after ten minutes you may feel like running for ten more. If you're after something more challenging, you will feel the endorphins bringing that "high" after a run, gym class, or other aerobic exercise.
Treat medical problems. Focus on activities of daily living (ADLs). Exercise.