more about fasting

A religious Fast requires total abstinence, not only from all food (unless bodily weakness do manifestly disable from holding out till the Fast be ended, in which case somewhat may be taken, yet very sparingly, to support nature when ready to faint), but also from all worldly labour, discourses, and thoughts, and from all bodily delights (although at other times lawful), rich apparel, ornaments, and suchlike, during the Fast ; and much more from whatever is in the nature or use scandalous and offensive, as gaudish attire, lascivious habits and gestures, and other vanities of either sex ; which we recommend to all Ministers, in their places, diligently and zealously to reprove, as at other times, so especially at a Fast, without respect of persons, as there shall be occasion.

Before the public meeting each family and person apart are privately to use all religious care to prepare their hearts to such a solemn work, and to be early at the Congregation. So large a portion of the day as conveniently may be is to be spent in Public Reading and Preaching of the Word, with Singing of Psalms fit to quicken affections suitable to such a duty: but especially in Prayer, to this or the like effect.

Book of Common Order