Anima Christi was written by an unknown author in the first half of the 14th century and Pope John XXII enriched it with indulgences in the year 1330. One can gain a 300 days indulgence every time the prayer is said. A 7 years indulgence if said after Holy Communion and a Plenary Indulgence if said every day for a month under the usual conditions.24

It is a prayer centered of the suffering and death of Christ. In it we seek union with His suffering, salvation from our sins, strength and protection against Satan, help at the hour of death and the hope of rejoicing with the saints forever.

It is a very meaningful prayer especially when said after Holy Communion.

Here I will provide the Latin, English and Sung version.

nima Christi, sanctifica me.
   Corpus Christi, salva me.
   Sanguis Christi, inebria me.
   Aqua letaris Christi, lava me.
   Passio Christi, conforta me.
   O bone Iesu, exaudi me.
   Intra tua vulnera absconde me.
   Ne permittas me separari a te.
   ab hoste maligno defende me.
   in hora mortis meae voca me,
   et iube me venire ad te,
   ut cum Sanctis tuis laudem te
   in saecula saeculorusm. 
               SOUL OF CHRIST
oul of Christ, sanctify me.
   Body of Christ, save me.
   Blood of Christ, inebriate me.
   Water from the side of Christ, wash me.
   Passion of Christ, strengthen me.
   O good Jesus, hear me.
   Within thy wounds hide me.
   Suffer me not to be separated  from thee.
   From the malicious enemy defend me.
   In the hour of my death call me.
   and bid me to come unto thee,
   That with thy saints 
   I may praise thee forever and ever. 
  Soul of my Savior sanctify my breast,
Body of Christ, be thou my saving guest,
Blood of my Savior, bathe me in thy tide,
wash me with waters gushing from thy side.
  Strength and protection may thy passion be,
O blessèd Jesus, hear and answer me;
deep in thy wounds, Lord, hide and shelter me,
so shall I never, never part from thee.
  Guard and defend me from the foe malign,
in death's dread moments make me only thine;
call me and bid me come to thee on high
where I may praise thee with thy saints for ay.