The 'Good' Part About Feeling 'Bad'

“The real money is to be made on the misery of others.”
The Chemical Buddha overheard this little piece of wisdom from the owner of the rehab center he had been ordered to attend by the Circuit Court of Jackson County. Good times. It did help solidify his vision of a better world … for him by turning his misery (and the lessons from it) into a spiritual movement, as well as helping other people become more miserable so they too could learn the same lessons. Has he been successful? Well, he died just as his labors were beginning to bear fruit. But we can attest to the fact that he did make several people miserable. Including himself.
What do you do that you know is not ‘good’ for you? Why do you continue to do it?
What do you learn about yourself by feeling ‘bad’? What do you learn by feeling ‘good’?