2-pack-a-day smoker here (~40 cigs per day), for over 10 years (twice that if you consider the time I was 1 pack or less a day).

I stopped smoking and started vaping for a while (~1.5 years) and went back to smoking after some bad vape experiences. At some point, even the smell of the liquid would cause me nausea.

My health is surprisingly good despite the habit. I walk every day, and I can do longer cardio without loosing breath or feeling tired. I'm either lucky or sitting on some ticking time bomb that went unnoticed so far.

I definitely recommend not starting on either though.