Lord Buddha described the factors giving rise to Effort (Viriya-sambojjhanga) as follows (Samyutta-nikāya, 19/367/96-97):
Monks, one must continuously and mindfully maintain effort with diligence and persistence. This feeds the Effort Enlightenment Factor (Viriya-sambojjhanga) which has not yet arisen to arise or the Viriya-sambojjhanga which has already arisen to progress and become complete.
The commentary explained eleven practices for giving rise to Viriya-sambojjhanga, developing it to perfection, and eliminating the Hindrances that dim and pollute Wise Vision (Chakkhu) (Samyutta-nikāya Atthakatha, 227-230).
1. Recognizing the dangers of the Unfortunate Realms (Apāya) means reflecting on the plight of world beings reborn in the Hells or Suffering Planes. For example:
This consideration will give rise to Viriya-sambojjhanga.
2. Constantly reflecting on the benefits of diligence means pondering that idlers cannot attain the Supra-mundane Paths, Fruits and Nirvana. Only the diligent can succeed. This consideration will give rise to Viriya-sambojjhanga.
3. Contemplating the Path to Enlightenment means considering the Arahatta-magga of Lord Buddha, the Silent Buddhas, and the Great Disciples. They all attained enlightenment. I, too, must achieve enlightenment, but this is impossible without effort. This consideration will give rise to Viriya-sambojjhanga.
4. Honoring alms donors means feeling and showing respect for those providing the four requisites such as food, thinking: They are not my relatives or servants, but they offer food expecting to make merit. A monk using these requisites can live in comfort to practice meditation for ending the suffering of the Triple Round. If I am lazy, I do not show respect for alms donors. Only a diligent monk deserves such alms. This consideration will give rise to Viriya-sambojjhanga.
Here is the story of a senior monk, Phra Maha Mittathera, who honored alms donors in this way. Phra Maha Mittathera lived in a cave named Kasaka and went on alms round to a village in which there lived a great laywoman who usually took care of him and treated him like a son. One day, before she went to the forest, she said to her daughter, “There are cooked rice, milk, ghee, and sugar cane juice. Warm up the rice and give all that to the monk when he comes. He is like your brother. You should have some too. Yesterday, I already had some crust of vinegar and rice that stuck to the pan.” Her daughter asked, “What will you have for lunch?” She answered, “Mix rice and bran to make Yāgu. Put some fresh vegetables with it and leave it for me.”
Phra Maha Mittathera accidently overheard this conversation and thought “This great laywoman has only a crust of vinegar and rice and Yāku or vegetables for lunch, but still has her daughter prepare food for me. She offers me food for the three gems. Can I give her those treasures? He realized that as long as he still had lust, anger and delusion, he did not deserve such fine alms food. So, he went back to his cave, put his bowl under the bed, hung up his robe, and then sat upright, resolving, “If I do not attain Arahatship I will not leave.” Thus, he dwelt without carelessness, developed Vipassanā and attained Arahantship before taking the meal. He became without defilements and worthy of gifts.
With a little smile, he left like a booming lotus. An angel in a nearby tree called: “Lord, I would like to pay homage to you, the highest of beings, without mental intoxicants (Āsava) and worthy of gifts.” The angel added, “If the great laywoman gives food to such a Perfect One, she will end all suffering.” Phra Maha Mittathera checked that it was still morning, so he took his bowl and robe to the village. Meanwhile, the daughter had already prepared the food and was waiting for the monk. When he arrived, she took his bowl, filled it, and put it in his hand. The monk gave his blessing, “May you be happy” and left. The daughter kept on looking at the monk because that day his complexion was so pure and his faculties so bright that his face glowed like a ripe sugar palm fruit. When the great laywoman came home from the forest she asked, “Did your brother monk come?” The daughter told the whole story and the mother knew that he had completed the monk’s obligation. She said, “Your brother monk is pleased with Buddhism and is no longer aroused by lust.”
Considering whether one’s behavior is worthy of Buddha’s inheritance means asking if one’s actions deserve being heir to the Seven Noble Treasures. This legacy is very refined; a lazy person cannot attain it. Parents of a misbehaving child might say, “This is not our child.” Similarly, the indolent disciple is not worthy of the Seven Aryan Treasures. Only those who exert effort will receive this priceless bequest. This consideration will give rise to Viriya-sambojjhanga.
Recalling that Lord Buddha is worthy of extreme reverence means contemplating that Ten thousand world elements (Loka-dhātus) shook upon His conception, His Great Renunciation, His enlightenment, His turning of the Dhamma Wheel, His Twin Miracles, His visit to the Deva World, His fixing the date for passing away, and His Great Decease or Parinibbāna. I have ordained in the religion of Lord Buddha. Is it appropriate for me to be lazy?” This consideration will give rise to Viriya-sambojjhanga.
7. Considering one’s birth station as worthy of praise means reflecting with pride on one’s social status. For example, that: I was not born an outcaste. I was born in the pure caste of King Okkakaraja, just after King Sammati, without any mixture from other castes. I was a nephew of King Suddhodana-maharaja and Queen Mahamayadevi. I am a brother of Phra Rahula. Thus, I am a son of Lord Buddha. It is not appropriate for me to be lazy. This consideration will give rise to Viriya-sambojjhanga.
8. Valuing companions who lead holy lives means contemplation such as: Phra Maha Thera Sariputta and Moggallāna [the Foremost Disciples] and the Eighty Great Noble Disciples were all very diligent and attained Supra-mundane Dhamma. How about me? Have I followed those Noble Companions? This will give rise to Viriya-sambojjhanga.
9. Avoiding lazy slackers means shunning those who have abandoned physical and mental diligence, like evading a python sleeping after a meal. This consideration will give rise to Viriya-sambojjhanga.
10. Associating with the diligent means joining with those who are strenuously resolute and energetically persevere. This consideration will give rise to Viriya-sambojjhanga.
11. Mindfully directing attention to diligence means constantly focusing directly on exerting effort towards enlightenment, in all postures, whether standing or sitting, etc. This consideration will give rise to Viriya-sambojjhanga.
The Effort Factor of Enlightenment Viriya-sambojjhanga arises due to these eleven causes and is fully developed to perfection when one attains Arahant Mentality.