In this scene of confusion and distraction

(J. C. Philpot, "Meditations on the Holy Spirit")

"The Spirit helps us in our infirmities. We do not
 know what we ought to pray for, but the Spirit
 Himself intercedes for us with groans that
 words cannot express." Romans 8:26

"We do not know what we ought to pray for."
How often do we find and feel this to be our case.
Darkness covers our mind;
ignorance pervades our soul;
unbelief vexes our spirit;
guilt troubles our conscience;
a crowd of evil imaginations, or foolish or worse
  than foolish wanderings distract our thoughts;
Satan hurls in his fiery darts thick and fast;
a dense cloud is spread over the mercy seat;
infidelity whispers its vile suggestions,
until, amid all this chaos, such confusion and
bondage prevail that words seem idle breath, and
prayer to the God of heaven but empty mockery.

In this scene of confusion and distraction, when all
seems going to the wreck, how kind, how gracious
is it for the blessed Spirit to come, as it were, to the
rescue of the poor bewildered saint, and to teach him
how to pray and what to pray for.

He is therefore said "to help us in our infirmities,"
for these evils of which we have been speaking are
not willful, deliberate sins, but wretched infirmities
of the flesh. He helps, then, our infirmities . . .
  by subduing the power and prevalence of unbelief;
  by commanding in the mind a solemn calm;
  by rebuking and chasing away Satan and his fiery darts;
  by awing the soul with a reverential sense
     of the power and presence of God;
  by presenting Jesus before our eyes and
     drawing forth faith upon His Person and work;
  and, above all, by Himself interceding for us and in
     us "with groans that words cannot express."

When the soul is favored thus to pray, its petitions are
a spiritual sacrifice, and its cries enter the ears of the
Lord Almighty, for "He who searches our hearts knows
the mind of the Spirit, because the Spirit intercedes for
the saints in accordance with God's will." Romans 8:27