This is probably the first prayer I learned by heart after the Our Father and the Hail Mary. I read it as a teenager, and it just moved and comforted me.
Soul 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
Never let me be separated from thee
From the evil enemy, defend me
At the hour of my death, call me
and bid me come to thee
That with thy saints I may praise thee
Forever and ever, Amen.
For a wonderful little book on this prayer, with meditations on each line, check out Anima Christi by Mother Mary Francis, P.C.C. from Ignatius Press.