You CAN change
always remember that the most important characteristic of a human being is that he or she can change. We are adaptable.
Quit smoking and your lungs will heal, stabilize your brain with exercise and diet and your depression will subside. These are not myths but straightforward facts. I have been very depressed in my life. I often remember telling myself "I can and have the power to change the way I feel". Stay positive, it's nearly everything.