For I know the plans that I have for you,’ declares the Lord, ‘plans for welfare and not for calamity to give you a future and a hope.’”
‭‭Jeremiah‬ ‭29:11 NASB1995‬‬ 
This is one of the most well-known verses in the entire Bible. It is often referenced as a source of comfort and hope by many Christians in many places. I’m sure it’s been that way for generations. 
But for whom is it true? Verse 13 tells us, it’s for those who “search for God with all their heart.” I’ve been wondering, practically speaking, what does that mean? And have learned that one way to answer this question is to look at the life of the man for whom the specific promise was fulfilled. 
Who Experienced Jeremiah 29:11?
The broader context of this oft-invoked passage is that God is speaking to His people in exile, and He’s telling them it’s not always going to be this way. 
Immediately before, “I know the plans I have for you…” God says, “When seventy years have been completed for Babylon, I will visit you and fulfill My good word to you, to bring you back to this place.” (Jeremiah‬ ‭29:10‬)‬‬
And immediately after, He says, “I will bring you back to the place from where I sent you into exile.” (Jeremiah‬ ‭29:14‬)‬‬
So this precious verse, quoted by Christians in all places and all times, was specifically spoken to God’s people who were in exile in Babylon, about their promised deliverance from Babylon. 
Who is the man who experienced this deliverance? From our study of Babylon to Jerusalem, we know that the answer is Daniel! It’s worthwhile to look at Daniel’s life and see, what did “searching for God with all his heart” look like? 
Seeing How Daniel Sought God
We can say lots about abstaining from foods as a young man, and seeking the Lord for wisdom concerning Nebuchadnezzar’s statue. We could talk about the lion’s den, and his freedom from fear. He was unwavering throughout his life. 
But there’s one specific thing that spoke to me as I read his story, and it’s at the very moment when he encounters the very promise of Jeremiah 29:11 in God’s Word himself!
“…I, Daniel, observed in the books the number of the years which was revealed as the word of the Lord to Jeremiah the prophet for the completion of the desolations of Jerusalem, namely, seventy years. So I gave my attention to the Lord God to seek Him by prayer and supplications, with fasting, sackcloth and ashes.”
‭‭Daniel‬ ‭9:2-3‬ ‭NASB1995‬‬ 
There’s that word, “seek.” Here we see Daniel “searching.” And in the next 15 verses, Daniel pours out his heart to God in prayer. We know, from our study of “Babylon to Jerusalem,” and from the immediate response from God that follows in verse 20, that this is where the fulfillment of the treasured promise began. 
We have placed the entire prayer below. Please read the next few verses, considering the question, “How is Daniel searching with all his heart?”
4 Alas, O Lord, the great and awesome God, who keeps His covenant and lovingkindness for those who love Him and keep His commandments, 5 we have sinned, committed iniquity, acted wickedly and rebelled, even turning aside from Your commandments and ordinances. 6 Moreover, we have not listened to Your servants the prophets, who spoke in Your name to our kings, our princes, our fathers and all the people of the land.
“7 Righteousness belongs to You, O Lord, but to us open shame, as it is this day—to the men of Judah, the inhabitants of Jerusalem and all Israel, those who are nearby and those who are far away in all the countries to which You have driven them, because of their unfaithful deeds which they have committed against You. 8 Open shame belongs to us, O Lord, to our kings, our princes and our fathers, because we have sinned against You. 9 To the Lord our God belong compassion and forgiveness, for we have rebelled against Him; 10 nor have we obeyed the voice of the LORD our God, to walk in His teachings which He set before us through His servants the prophets. 11 Indeed all Israel has transgressed Your law and turned aside, not obeying Your voice; so the curse has been poured out on us, along with the oath which is written in the law of Moses the servant of God, for we have sinned against Him. 12 Thus He has confirmed His words which He had spoken against us and against our rulers who ruled us, to bring on us great calamity; for under the whole heaven there has not been done anything like what was done to Jerusalem. 13 As it is written in the law of Moses, all this calamity has come on us; yet we have not sought the favor of the LORD our God by turning from our iniquity and giving attention to Your truth. 14 Therefore the LORD has kept the calamity in store and brought it on us; for the LORD our God is righteous with respect to all His deeds which He has done, but we have not obeyed His voice.
“15 And now, O Lord our God, who have brought Your people out of the land of Egypt with a mighty hand and have made a name for Yourself, as it is this day—we have sinned, we have been wicked. 16 O Lord, in accordance with all Your righteous acts, let now Your anger and Your wrath turn away from Your city Jerusalem, Your holy mountain; for because of our sins and the iniquities of our fathers, Jerusalem and Your people have become a reproach to all those around us. 17 So now, our God, listen to the prayer of Your servant and to his supplications, and for Your sake, O Lord, let Your face shine on Your desolate sanctuary. 18 O my God, incline Your ear and hear! Open Your eyes and see our desolations and the city which is called by Your name; for we are not presenting our supplications before You on account of any merits of our own, but on account of Your great compassion. 19 O Lord, hear! O Lord, forgive! O Lord, listen and take action! For Your own sake, O my God, do not delay, because Your city and Your people are called by Your name.”
What can we learn about what it means to “search for the Lord with all our hearts” from Daniel’s prayer? 
1 - an all-hearted seeker has no thought of his own righteousness
It’s remarkable to consider that, over the course of the entire prayer, there’s NOT ONE SINGLE MENTION of any of Daniel’s good deeds, but only his guilt and shame. There is no reference to anything that might commend Daniel to God. 
Despite all the “good” he had done in his life — this is after the lion’s den, after Daniel has been faithful in exile for 70 years — Daniel was not mindful of his own righteousness, but rather of his unworthiness. Read verses 5, 7, 10, 11, 13, and 15 above in that light. 
Daniel is one of the only people in the Bible whose story mentions no sin, yet his prayer is filled with his faults and empty of his merits. It’s clear that the one who searches with all his heart is taken up with God Himself and is not in the least taken up with himself. 
2 - an all-hearted  seeker knows that punishment is perfectly righteous of a holy God
Therefore the Lord has kept the calamity in store and brought it on us; for the Lord our God is righteous with respect to all His deeds which He has done...”
‭‭Daniel‬ ‭9:14‬ ‭NASB1995‬‬
You could imagine someone in Daniel’s shoes — just a boy when he was sent into captivity, who not only did not participate in the sins which sent him to Babylon, but had also conducted himself well while in exile — might resent God’s punishment, or view it as unfair. But he didn’t. He never wavered in his conviction of God’s perfect righteousness, even with respect to the terrible punishment he was enduring.
What a great picture for us! No matter how well we live, relatively speaking, ultimately, we are enemies of God, sinners, and vile offenders. No matter how much good we do, we must sincerely remember, “I absolutely deserve hell! That’s the proper place for me. I have no right to have any connection with God whatsoever. He Who dwells in unapproachable light is absolutely unapproachable.”
How easy it is to approach the throne lightly, and to cast off any thought of guilt or consequence from this side of the cross. But in so doing, we trivialize the immense price Jesus Christ paid for our sin. 
3 - an all-hearted seeker is primarily concerned for God’s name and glory
So now, our God, listen to the prayer of Your servant and to his supplications, and for Your sake, O Lord, let Your face shine on Your desolate sanctuary. O my God, incline Your ear and hear! Open Your eyes and see our desolations and the city which is called by Your name; for we are not presenting our supplications before You on account of any merits of our own, but on account of Your great compassion.
‭‭Daniel‬ ‭9:17-18‬ ‭NASB1995‬‬ 
This, to me, is the ultimate answer to the question, “What does it look like to seek God with all my heart?” We find the answer at the end of Daniel’s prayer, as he explains why approached God despite his total unworthiness and God’s total righteousness in punishing His people. 
Why did Daniel have the boldness to ask God to perform His word, despite his unworthiness?
Because of Who God is!
And why did he want God to fulfill His word? 
So that His name might be exalted. 
If you look at Daniel’s prayer, it’s clear that he doesn’t think even he has any merits to pray so boldly, or that there is any recipient in Israel worthy of God honoring His word. 
But Daniel doesn’t stop there, at his own unworthiness and the people’s unworthiness. Daniel goes on asking because  he has a concern for God’s reputation, which superseded even his own awareness of unworthiness. Daniel hates what it says about God that His people are a reproach. 
This reminded me of Moses’ passion for God’s name and reputation when the Lord threatened to destroy the people who had made the golden calf. “Why should the Egyptians speak, saying, ‘With evil intent He brought them out to kill them in the mountains and to destroy them from the face of the earth’? Turn from Your burning anger and change Your mind about doing harm to Your people.”
‭‭Exodus‬ ‭32:12‬ ‭NASB1995‬‬
It reminded me of Jesus, gloriously dismissing the price He was to pay when He was denied His ultimate joy — perfect fellowship with His Father — on the cross. “Now My soul has become troubled; and what shall I say, ‘Father, save Me from this hour’? But for this purpose I came to this hour. Father, glorify Your name...
‭‭John‬ ‭12:27-28‬ ‭NASB1995‬‬
Oh, to be cleansed of all other motives! Oh, that my overriding passion might be the excellency of the name of God, that the reproach on His name might be removed. 
This is what it means to seek the Lord with all my heart: His reputation has become my chief concern. That all my prayer and all my longing is for Him, for His name and reputation being redeemed in my life. That the burden of my heart in the midst of my circumstances might be that He would be vindicated and exalted. 
Not because of any merits of my own, but because God Almighty is totally worthy of an outstanding track record of faithfulness, love, and power. 
Father, glorify Your name.