Jesus told His disciples in Luke 18:1 - "...they ought to pray and not to lose heart"
He went on to tell the parable of the persistent widow, who persuaded a judge to take action for her by constantly coming to him until he did something for her.  And He said,
"Now, will not God bring about justice for His elect who cry to Him day and night, and will He delay long over them? I tell you that He will bring about justice for them quickly. However, when the Son of Man comes, will He find faith on the earth?" (Luke 18:7-8)
In the past month or so, the Lord has really gripped my heart with this exhortation that Jesus gave.
In our church we've often heard Brother Zac say to parents to pray for our kids consistently, regularly.
I have tried to do that with my wife and I see that prayer is like a leash that won't let them stray too far, it is a protection.  At the end of everything - when my kids get older and move on from our home, we will have made many mistakes looking back in raising our children, but can I at least be able to say that we prayed for them consistently?  That will be enough to cover all of our sins and lack and mistakes we made along the way.
I see the effect of the prayers others including my parents have had for me in my own life, and I'm convinced of the Lord's faithfulness to answer my own when I pray for my children.  I will set myself to pray for them and not lose heart or stop until they are born again, and to pray they will be disciples.
But one day this thought came to me which I’m convinced was a conviction from the Lord - the same faith which I am having to pray for my children, with persistence regularly and consistently; can I not pray for other important things in the same way?  Especially against my sin and UnChristlikeness which I see lingering on in me?
For example - if there's sin I've seen in my heart; some ongoing impatience, some root of bitterness toward someone, or subtle love of money where I give into some covetous thoughts for it, some slavery to food or addiction to electronics (like my phone), or some selfishness, some laziness, some spiritual dryness and lack of love for the Lord - can I set myself to pray consistently for deliverance until God helps me?
I have enough faith and burden for the salvation of my children, is not my own salvation from my sins (being saved from sin which is present in me today) equally as important, and deserve persistent prayer, until even the end of my life if needed?!
That thought has totally gripped me and changed my prayer life recently - if I pray and don't stop, the Lord will definitely answer.
These prayers can also be for others.  Some sin or slavery in someone else that I see, and I have a burden to see them delivered from.
I often remember how Hudson Taylor said, "I've learned to move man by prayer alone."  Can I not seek the Lord persistently to move in another person's heart?  My lost loved one, my coworker?  My brother who's struggling with some sin, slavery, discouragement or guilt?  We can knock persistently for bread for others - the Lord will also answer!! Jesus told the same parable in this regard for others in the parable of the friend at midnight (Luke 11:5-8)!
Maybe there’s something I need someone else to be moved for, for the sake of my family.  Suppose my child's school lost my child’s paperwork needed to enroll him, and he’s in danger of losing his spot and being moved to the wrong school.  Complaining is a sin, and it won’t do anything.  Instead, can I “move man by prayer alone?”  The bank made a mistake and overcharged by a lot of money, money that my family and I need, and I can’t seem to get through to the right person.  Can I move man by prayer alone? Praying until God helps?
I believe the Lord loves to see such faith where we lean on Him, and don’t leave Him.  Because faith is the thing that pleases God (Hebrews 11:6).
The world, when it's offered things freely (food, money, discount on material things, etc) crowds around the supply like ants until it's all gone!  There’s this thing in the U.S. called “Black Friday” where things are sold for huge discounts at many stores all over the country. Millions of people get up really early in the morning once a year to save a couple or few hundred dollars.  Some even camp in tents the night before.  Isn't it a wonder that the children of God don't storm God's throne with boldness like that for the things He's offering?  It's because of what Jesus said in verse 8 - there's no faith.
"When the Son of Man comes, will He find faith [the faith proved by persistence and not stopping until something is gained] like this?"
I heard someone once say, “The angels must be shocked at the mountain of blessings, just sitting there in Heaven, left unredeemed by God’s children, simply because they didn’t come and ask.”
On the same note, there must be so much joy in Heaven where some rare one prays and doesn’t give up, and makes it through to that treasure to take of it.  And the angels say, “Finally!!!! Someone who sees the vast eternal value in what the Lord has to give!!”
And these people may not appear zealous or excited on the outside.  It may just be their personality. Real zeal isn’t necessarily shown by a persons personality and emotions.  Real zeal and faith is proven by persistence.
It’s possible we can think we asked, having not really asked.  We pray once or twice (maybe even with tears) for something and we see nothing happen, and figure "Well that didn't work, I guess I'll move on.”  That’s not asking. And that’s not faith. It doesn’t matter how many tears there were in those 2 prayers.  The prayers stopped; that's the proof it wasn't a real burden or faith.
Faith also means burden.  Burden to where, we will pray until the day we die if we have to for God to do something. Real faith and burden means never stopping.
And we can get discouraged when God doesn't answer, and wonder why - all the time not realizing that, the reason He is delaying is because He's doing a lot more than just answering what we're praying for.  His ways are so much higher than ours (Isaiah 55:9).  He doesn't only want to change our situation through our prayer, He wants to change US.
Prayer doesn't just change our situation it changes us!
The Lord has changed my life recently through this word of Jesus, and I'm so thankful He's given me a confidence in this parable of the persistent widow, that if we pray and do not lose heart, in due time we will break through and take freely from the spiritual mountain of treasure He has for us, if we only have the faith of persistence.
Whatever sin you’ve struggled with, whatever inward struggle you’ve had - lack of joy, slavery to anger or lust, anxiousness, fear, lukewarmness toward the Lord - whatever burden you have for another, whatever foothold Satan has had in your home or your marriage, whatever unmet need is left in your life or in your home -
Grab ahold of Luke 18 today and the Lord’s promise - break through (as long as it takes) to the treasure that God has freely for you, “pray and don’t lose heart.”  Pray everyday, even a couple of minutes for these things - the main thing is just pray with burden from your heart in those 2 minutes, and pray regularly, daily - and don't stop.  Even if it takes years or decades!  He will answer, and even more importantly, He will be glorified and pleased by your persistent faith.