This was the promise contained in the letter from the Prophet Jeremiah to the Jews who were being held in captivity in Babylon. God wanted to comfort and remind his people that he was available to those who would take the time to seek after him. God desired sincerity of the heart and a people who would not only seek after him with words. God desires our hearts and he knows when we are sincere before him.
And without faith it is impossible to please him, for whoever would draw near to God must believe that he exists and that he rewards those who diligently seek him. (Hebrews 11:6) Seeking after God requires faith and without faith it is impossible to please Him. Seeking God requires a belief in his existence and the knowledge that once we find him that we will be rewarded.
Seeking God results in the ability to rest in his presence and find comfort and shelter in him. He that dwells in the secret place of the most High shall abide under the shadow of the Almighty. (Psalm 91:1) Being in the presence of God brings safety, protection, shelter and provision. There is no way that you can be around God and not have access to his blessings.