You must be a deeply anxiety-ridden person, otherwise...

You must be a deeply anxiety-ridden person, otherwise chain-smoking is not possible; chain-smoking is a by-product. You must be so concerned about a thousand and one disturbances inside, you must be carrying such a big load of worries on your heart, on your chest, that you don't even know how to forget them. You don't know how to drop them - smoking at least helps you to forget about them.