Shasti, or Sashti, is an important viradha day in a Tamil (Hindu) calendar and fasting on this day is dedicated and associated with Lord Muruga (Kandha/Karthikeya). Shashti days in a month falls on the sixth day of every lunar month in traditional Tamil Hindu calendar. The Shasti (Thithi) falling during the waning phase of the moon is chosen for fasting (viradha) by Lord Kandha / Karthikeya / Subrahmanya / Muruga devotees. Of the two Sashti (Thithis) in a month, the Shashti occurring after the new moon (Amavasya), Skanda devotees observe partial or full fasting.
Shasti Vratam (சஷ்டி விரதம்)or Upvaas (உபவாசம்) dedicated to Lord Muruga or Kartikeya is observed by his devotees on this day by reciting skanda sasthi kavacham. People busy in this modern world recites Kanda sasthi kavacham at home and some finds time to visit Lord Muruga temples and meditate and listen to stories of God Muruga, reading Skanda Purana or reciting Skanda Sashti Kavasam. Also people recites pranava manthra "OM SHARAVANA BHAVAYA" and receives the blessings by making Lord Muruga happy.
Kanta Shasti Vratam is the best and auspicious time to worship Lord Muruga which is observed once a year in the month of ‘Aippasi' (October–November) starting from the ‘piratamai (பிரதமை)' the 1st phase of the brightening moon.
Shasti viratham is known for maintaining good health. Once in a year, giving 6 days OFF for our digestive system improves the body health . Even lot of doctors suggested to follow fasting in routine life. Skanda sasthi vratam, the effective viratha for ladies those who are trying to conceive. Its believed that by worshipping and fasting on Kandha Sashti Days benefits the couple and will surely be blessed with children on doing this vratam.
The Shasti fasting begins from the morning with sunrise. The fast is broken on the next day morning after praying to Lord Surya (Sun God). Most people observing the fast visit Murugan Temple on this day.
A full day fasting is observed in many places. Due to jobs and health related problems some skip food for two timings usually have a single meal in the afternoon or night.
Devotees of Lord Muruga listen to stories related to Skanda (Muruga) and reading of Skanda Purana. Main activity on Kandha Shashti day is the reciting of Kanta Shasti Kavasam.
Fasting is not just abstaining from food but it also an attempt to instill positive thoughts. Many people use fasting as a means to fight against anger, lust, impatience and other negative tendencies. All Vratas associated with Hindu religion is an attempt to realize the Brahman.