Proverbs 4:23 "Keep thy heart with all diligence; for out of it are the issues of life."
Don't let anyone convince you that it is selfish or wrong to care for your own heart. If your own heart is not cared for, you will not be free to help the hearts of others.
The Old Testament gives us several examples of men who strengthened themselves – some strengthened themselves to do wickedly; some strengthened themselves in the Lord to do His work.
Though sometimes, we have precious friends and family who uplift us and minister to our spirits, there are imminent times when Jesus is the only One Who truly understands our hearts. We must strengthen our own hearts in God, finding refuge in Him, letting Him minister to our heart needs.
"Only take heed to thyself, and keep thy soul diligently, lest thou forget the things which thine eyes have seen, and lest they depart from thy heart all the days of thy life: but teach them thy sons, and thy sons' sons;" –Deuteronomy. 4:9
O ut of a heart well kept will flow living issues, good products, to the glory of God and the edification of others. Or, in general, all the actions of the life flow from the heart, and therefore keeping that is making the tree good and healing the springs. Our lives will be regular or irregular, comfortable or uncomfortable, according as our hearts are kept or neglected." -Matthew Henry
“Search me, O God, and know my heart: try me, and know my thoughts: And see if there be any wicked way in me, and lead me in the way everlasting.” -Psalms 139:23-24