Mahamrityunjaya mantra is the propitiation of Lord Shiva because Shiva is thought to represent the truth and death is the ultimate truth, which is ruled by Lord Shiva. Mahamrityunjaya mantra anushthana (japa) is performed when someone is running markesh, a planetary period invested with powers to inflict physical harm, or when someone’s health is causing serious problems or when some major operation is to be performed.

Mahamritunjay Mantra

"Om Hom Joom Sah Om Bhur Bhuvah Svah
Om Trayambakam Yajamahe Sugandhim Pushtivardhanam
Urvarukvamiva Bandhanan Mrityormukshiya Maa Mritat
Om Bhur Bhuvah Svah Om Sah Joom Hom Om"

If this mantra is chanted for 1,25000 times or its half 62,500 with complete devotion and faith then a person can even return from the jaws of death. Dashmansh, one tenth additional Mahamrityunjaya mantra chanting is also essential afterwards.

Mahamrityunjaya mantra chanting is also a form of propitiating Lord Shiva so that the person may be released from the bondage of death and nourished with nectar bestowing a fresh lease of life.