It's no secret that quitting smoking can predispose to a long-lasting depression.
A doctor of mine once told me a story:
He had a good friend who was a smoker for 30-some years before he quit. This man used to love going for walks in his large backyard; it was something he did almost every day.
Once he was visiting with my doctor, about 2 years or so after he quit smoking. He said, "You know what Doc? I feel better than I ever have - I can breathe easily, I can taste and smell like I never have in my life, I can go up stairs with no problem at all... but there's just one thing that's really been bothering me..."
Doc said, "What is it?"
The man said, "I don't really enjoy my walks anymore."

A doctor of mine once told me a story:
He had a good friend who was a smoker for 30-some years before he quit. This man used to love going for walks in his large backyard; it was something he did almost every day.
Once he was visiting with my doctor, about 2 years or so after he quit smoking. He said, "You know what Doc? I feel better than I ever have - I can breathe easily, I can taste and smell like I never have in my life, I can go up stairs with no problem at all... but there's just one thing that's really been bothering me..."
Doc said, "What is it?"
The man said, "I don't really enjoy my walks anymore."