Today is Ekadasi, if possible, observe it without even drinking water
(nirjala), or take a little prasada once in the day if this is not possible.
Many old people, who are lean and thin, can observe nirjala Ekadasi ; so why not those of you who are young and strong? Try to observe it like this. However, if by such fasting your head pains and you go to sleep, then what is the use?
Try to remember Krsna, associate with Vaisnavas, read the Vedic scriptures, and offer prayers day and night.
Sri Srimad Bhaktivedanta Narayan Goswami, from a lecture February 1997 in Murwillumbah
Also see: Ekadasi : Mother of Prema-Bhakti