Not sure why you are being downvoted - this type of comparison fails spectacularly as you are not dealing in concrete events. From statistics, we know that on a

Not sure why you are being downvoted - this type of comparison fails spectacularly as you are not dealing in concrete events. From statistics, we know that on average over a large number of deaths, smokers tended to live slightly shorter lives. This is largely because of emphysema and similar which shortens the lives of smokers in aggregate. Exercising every day is not going to keep you alive if you die from emphysema, so there is no 'cancel out effect' in practice.