Charles Haddon Spurgeon wrote:
"Never give up praying, even when Satan suggests that prayer is in vain. Pray in his teeth! "Pray without ceasing," (I Thess. 5:17). If the heavens are brass and your prayer only echoes above your head, pray on!
If month after month your prayer appears to have miscarried, if you have had no answer, continue to draw close to the Lord.
Do not abandon the mercy seat for any reason. If it is a good thing that you have been asking for, and if you are sure it is according to the divine will, wait, tarry, pray, weep, plead, wrestle, and agonize until you get what you are praying for.
If your heart is cold, do not wait until your heart warms. Pray your soul into heat with the help of the ever-blessed Holy Spirit, who helps our weakness, who intercedes for us with groanings too deep for words (Rom. 8:26).
Never cease prayer for any reason. If the philosopher tells you that every event is fixed and that prayer cannot possibly change anything, go on praying.
If you cannot reply to every difficulty that man suggests, resolve to be obedient to the divine will.
"Pray without ceasing." Never, never, never renounce the habit of prayer or your confidence in its power."