My vote that you didn't ask for is to quit smoking. COVID 19 is a respiratory virus. Smoking isn't going to help your chances if you do get it.
You can stay sober and quit smoking at the same time. I quit smoking and drinking - so have a lot of people. If I can do it.
I'm not sure I could also quit eating actual food at the same time though! I don't do well on meal replacements. Maybe one meal a day sometimes, like when I'm really busy but food is a pleasure and I want to have meals.