Several, including one friend that pondered it for months before committing...people have to move at their own speed.
They'll also have their OWN reason...money, health, not smoking around a baby, etc - and THAT reason is the only thing that matters to them.
People resist change. It's human nature and happened with all technology. You pretty much have to remember that we're all in the first or second wave.
Also remember that you can't save everyone, and don't beat yourself up when someone that REALLY needs it (again, health or saving money vs a daily cig habit) isn't interested in converting - they are who they are, and you are NOT going to change them.
Lead by example, and answer questions when asked...simple as that.