How long has this feeling been going on? You sound depressed---often medication can be helpful for that but also cbt. One of the things I learned in cbt was that laughing by yourself for 10 minutes can help cheer you up...its sort of like how just smiling can make you feel a little better.

Another thing is self care but you need to find pleasure in something for that to work. Basically you add up your favorite things, not necessarily accomplishments but whatever you like to do. Your interests indicate coffee and smoking and writing, so do all three at once and see how you feel. Does going to a coffee shop feel better than being at home alone...then do that. Alternately maybe you can learn about different aspects of coffee, like how to make a latte at home, what varieties there are how much better freshly ground tastes. Maybe you can organize some sort of tasting party where everyone brings a different variety(try inviting the people from your work).