THis stuthi can be recited by man, woman,child at any time anywhere - there is absolutely NO restrictions on chanting - please understand restrictions were imposed so that there was discipline [ of some sort atleast ] while religious practices were followed - mainly because of human nature being what it is we will relax norms to suit our laziness and degradation will set in ! The restrictions for maintaining purity - like after a bath, etc. naturally apply - this too, in case of the old / infirm can be waived if one is so keen on chanting. Learning from a Guru, again, is more so when everything was transmitted orally and there were no recordings or the printed word !