This mantra is a prayer to Shiva, the lord of destruction, penance and meditation, for help overcoming death. The seeker is more concerned with avoiding spiritual death rather than physical. The mantra is a request to Shiva to lead us to the mountain of meditation. It is one of the most potent of the ancient Sanskrit mantras. It is a call for enlightenment and a practice of purifying the karmas of the soul at a deep level. It is also said to be beneficial for mental, emotional and physical health.
ॐ त्र्यम्बकं यजामहे
सुगन्धिं पुष्टिवर्धनम् ।
मृत्योर्मुक्षीय मामृतात् ॥
Om Tryambakam Yajāmahe
Mrtyor-Mukssīya Māmrtāt ||
1: Om, We Worship the Tryambaka (the Three-Eyed One),
2: Who is Fragrant (as the Spiritual Essence), Increasing the Nourishment (of our Spiritual Core);
3: From these many Bondages (of Samsara) similar to Cucumbers (tied to their Creepers),
4: May I be Liberted from Death (Attachment to Perishable Things), So that I am not separated from the perception of Immortality (Immortal Essence pervading everywhere).
or simply :
We pray to Lord Shiva whose eyes are the Sun, Moon and Fire may he protect us from all disease, poverty and fear and bless us with prosperity, longevity and good health.