>>34727924doesn't the knowledge of your depression helps you to doubt and ignore what your sad periods make you think? it should.
go about your life without having your emotions dictate your thoughts. be wary of what thoughts you have when you're depressed and don't take them seriously. if you need to, write down what your plans are in a diary. then, a week later or so look back and see if you are drifting away from them, and ask yourself: 'why did it happen?'.
if you have a realistic goal, you have no excuse to feel you can't accomplish it. cram that into your head. you're enough human material to accomplish great things, more than you may believe today.
allow yourself to feel sad if *besides your efforts* you still feel sad. in the next day, take action and occupy yourself with some activity that improves your life.
know that your body is a machine that needs maintenance, and if it's too long without maintenance it will go from a smooth operation to a clumsy one, and that will stress your mind.
the opposite is also true. if your mind is clumsy it will put your body into unnecessary stresses for pure lack of knowledge or calibration.
your duty is to do what is right. your self-respect and the solid conviction that you're worth will save you from, say, suicide - be it long-term suicide through bad habits, addictions and bad relationships, or be it from abrupt self-end.