3You will guard him and keep him in perfect and constant peace whose mind [both its inclination and its character] is stayed on You, because he commits himself to You, leans on You, and hopes confidently in You.
I found this verse to be so profound and it speaks of promises that no one can ever fulfill except the Lord Most High. Sometimes it is true that God will help those who help themselves first but never without giving the blueprint and a map (Bible). We just got to stay on track with Him and merciful as He always is, He will nudge and pull us back if we go off the wrong way.
As He has written in Isaiah 26:3 , pay attention to the words perfect and constant peace then whose mind is stayed on You, commits, leans, and hopes confident. Sounds so perfect and human nature perpetually fails to meet near its requirements. But is it impossible? I believe not (though I struggle immensely in this area.)
God is saying it is possible that we can train ourselves to capture God's divine peace in times of turmoil, to stand on the pool of peace with faith like a little child. When I read the word commits, leans, hopes confident , it reminds me on a little baby or toddler who fears nothing and is in perfect peace when in the arms of his mother. Like the world would crumble and he would know no fear because he knows his mother will do all she can to guard (to protect), keep him in perfect peace( away from harm).
Remind yourself of His promises each morning, memorize and keep it close to your heart.