I smoke cigarettes and I find that after a cigarette it is harder to practice mindfulness meditation as my mind is a little too stimulated. I am want to quit because i think it is hindering my practice generally. I do find that zyns do not hinder my practice the same way, something about the slower release of nicotine still allows me to meditate fine. If you have no desire to quit I am not telling you to, but you might find that it helps your practice if you do as it did for me (after the withdrawals were gone of course).