During an illness first of all entrust yourself to God in order to strengthen your spirit in the midst of your misery.
From the Works of Platon - Bishop of Kostroma
Often remember and think of the suffering and the death of Jesus Christ. Ceaselessly say all the prayers you know and can, then beg God to forgive you your sins and to give you patience while ill. In all ways possible abstain from complaining and irritation which are common when ill. Our Lord Jesus Christ underwent, for the sake of our salvation, the most painful illness and sufferings, and what have we done or suffered for the sake of our salvation?
Go to the services in church as often as possible and try especially to be present often at the Liturgy. Attend on Sundays and Holy Days without fail, and do deeds of piety; always remember that you are in the presence of God, the Angels and the Saints; the remaining time devote to pious reading and other acts of piety and love.
Devote your birthday and Saint's Day especially to pious deeds.
Every year and every month examine your conscience rigorously. Go to confession and receive the Holy Sacraments as often as possible. Receive Holy Communion always with sincere hunger and real thirst of your soul, with a contrite heart, with reverence, humbleness, faith, trust and love. Think of the sufferings and death of Jesus Christ as often as possible, begging Him to veil your sins and receive you into His Kingdom.
May the name of Jesus always be on your lips, in your soul and your heart.