Since having past [negative] karma, [to be] bothered [by] loathsome sickness, [you] should eat [as a] veg[etari]an, [and practise] mindfulness [of] Buddha, for past lives’ [karmic] enemies doing practices, [for their] transcendence [and] deliverance.
That said, [for] transcendence [and] deliverance, [there is] likewise no need [to] invite monastics [to] conduct Buddhist ceremonies, only [with] oneself seriously, earnestly [and] utmost sincerely mindful [of Amitābha] Buddha [i.e. Āmítuófó], and[/or] mindful [of] Guānyīn [Bodhisattva] only.
Moreover, [do] not say, ‘[Is] only [being] mindful [of] one Buddha [and/or] one Bodhisattva, then able [to] heal sickness?’
[You] must know [that] mindfulness [of] Buddha [is], of [the] Buddha’s teachings within, [the] most perfect, [complete], sudden [and] straightforward teaching, [with] its benefits surpassing all [other] Dharma doors.
[It is] only with [the] mind, [being with] sincerity [or] no sincerity as different grades, not [the] teaching having either efficacy or no efficacy.
Pure Land Tradition’s 13th Patriarch Great Master Yìnguāng
(Reply Letter To Xiāngyīn Layperson Huáng Sòngpíng)
 There should be eating as veg(etari)ans as many, if not almost all sicknesses, arise from unhealthy consumption of animal products, that also creates negative karma which ripens as sicknesses. While eating as veg(etari)ans helps heal the body, mindfulness of Buddha helps to heal both body and mind, by eradicating the negative karma involved.
 As we have lived many past lives as unenlightened beings, it is inevitable that we have incurred karmic creditors’ [i.e. enemies], whom we are not aware of. (They might not even remember us as enemies, yet instinctively behave as our enemies.) As such, we should always have good will to practise as taught sincerely, and to dedicate merits to all beings sincerely, to help alleviate their suffering, and to transcend rebirth by being delivered to Pure Land.
 Mindfulness of Buddha is the most perfect, complete, sudden and straightforward teaching, as all Dharma practices are perfected and completed upon perfect and complete mindfulness of Buddha – even for great Bodhisattvas, as they have to be mindful all the way, of who they aspire to finally become – Buddhas. It is a straightforward teaching for sudden enlightenment as once Buddha is connected to firmly, especially in Pure Land, this leads swiftly to enlightenment. Being the most straightforward spiritual path, it is thus the swiftest path to Buddhahood, with benefits surpassing all other Dharma doors.
 Mindfulness of Āmítuófó and/or Guānyīn Púsà (i.e. Bodhisattva) were probably taught to offer them as optional subjects of mindfulness, not so much of it being essential to practise mindfulness of both. We know this is so as Āmítuófó is also known as the ‘Unsurpassable Great King Of Healers’ (无上大医王), which means mindfulness of his name will suffice for healing. Perhaps Guānyīn Púsà was mentioned as many associate her with alleviating of suffering in everyday life, while associating Āmítuófó more for receiving and guiding for birth in Pure Land at the end of life. However, just as Guānyīn Púsà also assists in receiving and guiding at the end of life, Āmítuófó also heals in everyday life.
 When severely sick, to the point of already possibly dying, thus having low possibility of healed in this life, there should be focus only to reach Pure Land, as detailed in the ‘Related Letter’ below. It is via reaching Pure Land that there will be complete and lasting healing.
Namo Amituofo : Translation and notes by Shen Shi’an
What Attitude To Have When Severely Sick?