Mannaz is the letter M
Anglo-Saxon Rune Poem (from ragweedforge.com)
The joyous man is dear to his kinsmen;
yet every man is doomed to fail his fellow,since the Lord by his decree will commit the vile carrion to the earth
Mannaz reversed indicates a day of mental and spiritual laxity. It is okay to take a break sometimes, to allow yourself to ride on the laurels of your effort, and just take it easy. Sometimes choices made early make this a necessity, as sleep, sustenance or the demands of physical life just need to be met before the work of magic and spirit can be met.