Lord Rām was already exhausted in the battle fighting the demons. And now he was faced with the all-powerful Rāvana who was well prepared for the ensuing battle. Lord Rām was in deep thought while looking at Rāvana with full concentration. Sage Agastya and all other Gods had come to witness this epic battle. Seeing the worry and tiredness on Lord Rām’s face, sage Agastya came to Lord Rām and gave him the secret wisdom of Sun worship through Āditya Hridayam.
There are 31 verses in Āditya Hridayam and the following 2 are my favorite.
राम राम महाबाहो शृणु गुह्यं सनातनम् |
येन् सर्वानरीन वत्स समरे विजयिष्यसि ||
Rām Rām Mahābāho Shrunu Guhyam Sanātanam |
Yen Sarvānrin Vatsa Samare Vijayishyasi ||
MEANING: ‘O Rama’, ‘O Mighty armed elegant Rama’, listen carefully to the eternal secret by which, ‘O my child’, you shall conquer all your enemies on the battle field and win against your adversaries.
सर्वमङ्गल माङ्गल्यं सर्वपापप्रणाशनम् ||
Sarva Mangal Māngalyam Sarvapāp Pranāshanam |
Chintā Shok Prashamana Māyurvardhan-Muttamam ||
MEANING: This supreme prayer is the best amongst auspicious verses, it will destroy all sins, dispel all doubts, alleviate worry and sorrow, anxiety and anguish, and will give longevity and complete prosperity.
FULL HYMN: This is my favorite rendition of Aditya Hridayam: https://www.youtube.com/watch?v=DIKjaNjN2rA.
Chanting of Āditya Hridayam is especially beneficial on Sundays.
Om Suryāya Namaha!