smoker's remorse
The feeling you get when you light up a cigarette, then halfway through, you realize you don't feel like smoking it anymore.
Dude, you wanna finish my cigarette? I've got a bad case of smoker's remorse.
Smoker's Remorse
Regret of one's negative decisions that have placed them in their current situation, such as smoking leading to lung cancer, causing regret.
Tom: My mom is upset because she's gotten so fat she can't see her toes for her stomach.
Mike: That's just smoker's remorse. She shouldn't have sat on her ass so much.
Mike: That's just smoker's remorse. She shouldn't have sat on her ass so much.