There are people who think continually nagging God for this or that will get results, citing the reference made by the Lord Jesus in Luke 18:1-8; 
Luk 18:1  And he spake a parable unto them to this end, that men ought always to pray, and not to faint;
Luk 18:2  Saying, There was in a city a judge, which feared not God, neither regarded man:
Luk 18:3  And there was a widow in that city; and she came unto him, saying, Avenge me of mine adversary.
Luk 18:4  And he would not for a while: but afterward he said within himself, Though I fear not God, nor regard man;
Luk 18:5  Yet because this widow troubleth me, I will avenge her, lest by her continual coming she weary me.
Luk 18:6  And the Lord said, Hear what the unjust judge saith.
Luk 18:7  And shall not God avenge his own elect, which cry day and night unto him, though he bear long with them?
Luk 18:8  I tell you that he will avenge them speedily. Nevertheless when the Son of man cometh, shall he find faith on the earth?

   And though I know many are taught to “ask and keep on asking, seek and keep on seeking, knock and keep on knocking”, is that really what God wants?  Keep in mind, the scripture clearly says in Luke 11:9  And I say unto you, Ask, and it shall be given you; seek, and ye shall find; knock, and it shall be opened unto you.   Had the Lord Jesus meant, “keep on asking, keep on seeking, keep on knocking”, don’t you think He had a good enough command of the language to say so?  But He didn’t say to keep it up. He said men ought always to pray and faint not, meaning, not to stop praying.  You don’t have to keep praying the same old thing over and over!  That is UNBELIEF! 
    Take a good look at Luke 18:6-8 says, Hear what the UNJUST JUDGE saith.  He didn’t say, Hear what the LORD saith.  God is not an unjust judge.  Shall not God avenge His own elect, which cry day and night unto him, though he bear long with them?  Why is He bearing long with them?  Could it be because they are continually whining to Him?  The key to this is verse 18: I tell you that he will avenge them speedily.  Nevertheless when the Son of man cometh, shall he find faith on the earth?  Just what did the Lord Jesus mean by that question: shall he find faith on the earth?  Will he find someone who will ask once and know it’s done?  Will he find someone who does not have to keep asking over and over, even though he has already said “YES”?  Will he find someone who will pray according to Mark 11:24 and “believe they receive” and praise God they have it, even before they see it?  Or will he come and find us still asking and asking and asking, never believing it’s done until they can see it with their eyes?   Men say, “I’ll believe it when I see it.”  God says you’ll see it when you believe it: and not a moment before.
    1 John 5:14-15 says,  And this is the confidence that we have in him, that, if we ask any thing according to his will, he heareth us: And if we know that he hear us, whatsoever we ask, we know that we have the petitions that we desired of him.
    Do you see anything there telling us to just keep on asking?  If we have the confidence in Him we are supposed to, and we pray according to His will, we only have to ask once.  How do we know what His will is?  Glad you asked!! READ THE BIBLE!!  It is the written record of His will.  If you want to know what God has to say about any given subject, it’s there, read it, and you’ll know whether God is for it or against it, and pray with that knowledge.  Now, if you need healing, and you read the Gospels, you will quickly see the Lord Jesus healed all who came to Him, NEVER refusing to heal anyone.  It is written: Jesus Christ the same; yesterday, today, and for ever.  So we know He won’t change His mind tomorrow about what He did two thousand years ago.  When we ask according to His will, it says “he heareth us”.  The Lord Jesus isn’t hard of hearing, He heard you the first time you asked.  So leave it alone.  Suppose I asked to borrow five dollars from you and you said “YES”. And I stood there with my hands in my pockets and just kept on asking, “May I borrow five dollars from you?”  How many times would it take me asking before you got just a little tired of me asking, hmmm?  But we do this to God every day. 
   OK, moving on: And if we know that he hear us, whatsoever we ask, we KNOW that we have the petitions that we desired of him.  Why do we know?  Hello!!  Because we did our homework., so we know what is “yes”, and we know what is “no”.  Does it say “we know we have the petitions we desired of him because we hollered and whined and asked and asked and cried all the day long?  No.  But yet we insist upon making the LORD bear long with our continual doubt and unbelief.  When will we grow UP?  Can you see where the Lord Jesus instructed His disciples to ask and ask and ask for someone to be healed?  No, He commanded them HEAL the sick.  You can’t heal the sick if you’re spending all your time asking and keeping on asking, seeking and keeping on seeking, and knocking and keeping on knocking.  You’ll just wear yourself out, plus you’ll show God you didn’t “believe you receive” the FIRST time you asked.  And you’ll just keep going around that same old mountain, time and time again until you have worn yourself a rut in the mountain.  You’ll never get any work done for God like that.
    So the next time before you pray about anything, arm yourself with the knowledge of what God has to say about it, then praise Him and thank Him, and pray according to the Word, and believe it’s done.  Thank Him the way you would if you prayed, and thirty seconds later, you saw it happen.  You’d soon learn to thank Him before you even prayed.  That’s what I do.  Psalm 100:4 tells us: Enter into his gates with thanksgiving, and into his courts with praise: be thankful unto him, and bless his name.  I would never dare bring my petition before God for any reason without first giving Him thanks and praise and blessing His name.  Why?  Because He is Almighty God, and we are instructed to so so.  Receiving from God isn’t hard if you go about it His way.  Believe me, God wants you to have your prayers answered more than you do, but He does everything according to His Word.  So read the Word, and you’ll know how to pray once and it’s done.