Modern dental surgery doesn't really hurt. It is uncomfortable, but rarely will you suffer any significant amount of pain if you follow all instructions given to you by the dentist. You should probably take a couple of pain killers as soon as you're able to drink liquids after the surgery, because once the numbing effect wears off, you may experience pain for a short while (I recently had an extraction and this is precisely what happened to me--trust me, don't take the chance, just take the pills). Root canals do not intrude into the tissues of the mouth the way extractions do, so you're not likely to experience much, if any, discomfort. At worst you will have minor pain localized in that one tooth, but you will find yourself quite capable of moving on with your life almost as if nothing happened. Just be sure to get a proper crown done within a few weeks. If you don't, your tooth may literally crumble inside your mouth.