There is a very significant, but little known grant of a plenary indulgence that is available to the Catholic faithful on the Fridays of Lent.

From the Handbook of Indulgences: A plenary indulgence is granted on each Friday of Lent and Passiontide to the faithful who, after Communion, piously recite the following prayer before an image of Christ crucified; on other days of the year the indulgence is partial.

(This is my preferred translation of the prayer)

Behold, O good and most sweet Jesus,
I fall upon my knees before Thee,
and with most fervent desire beg and beseech Thee
that Thou wouldst impress upon my heart
a lively sense of faith, hope and charity,
true repentance for my sins and a firm resolve to make amends.
And with deep affection and grief, I reflect upon Thy five wounds,
having before my eyes that which Thy prophet David spoke about Thee, O good Jesus:
“They have pierced my hands and feet, they have counted all my bones.”
Amen.

(And here is a more contemporary translation)

Behold, O kind and most sweet Jesus,

I cast myself upon my knees in Your sight,

and with the most fervent desire of my soul I pray and beseech You
that You would impress upon my heart
lively sentiments of Faith, Hope, and Charity,

with true repentance for my sins, and a firm purpose of amendment,
while with deep affection and grief of soul I ponder within myself and mentally contemplate Your five most precious Wounds;
having before my eyes the words which David in prophecy spoke concerning Yourself, O good Jesus:

“They have pierced my hands and feet; they have numbered all my bones.”
Amen.

NOTE – To obtain the indulgence the usual conditions apply: Confession, Communion, prayers for the intentions of the holy Father and freedom from attachment to sin.