Hi. Here's a potentially easy request.

I'm in the early stages of writing a novel and one of the characters chain smokes cigarettes. The smoking probably doesn't really affect him much or at least in certain ways (because sci-fi/fantasy reasons. Most notably, supernatural willpower means he's not really addicted at least not at at this point in the story; He just keeps doing it even though its bad for him because he's spiteful and self-hating...), but I haven't decided how much they do affect him and I feel like to have this idea work best and in the ways I want it to, I need to know more about smoking. So I figured I'd make this thread.
Please don't answer this thread unless you know what you're talking about; I'm just using this primarily to show that the character is wasting themselves and/or doesn't care about life. I'm trying to get through the noise about nicotine, so if you're a smoker or know a smoker well enough to answer, great.

I might have more questions in the future, but most importantly, I need to know how many cigarette packs used in a single smoking session and how many sessions per day would be:

*Not believable (roughly)
*Ridiculous, but plausible
*Heavy
*Regular
*Relatively light

Other info appreciated I guess, like maybe how it specifically affects athletics (found a lot of noise...), but please don't dump a big wall of text on me and please stay focused on giving me information about realistic smoking rather than writing advice. I want to know what people might expect.