Having a Settled Soul is all about 1st knowing Jesus Christ as your Savior and 2nd its about obedience to HIm.  I have learned over time that life is so much better and my Soul truly is Settled when I am living in Obedience to my Savior.  Our Soul is designed to Know God and when it doesn't know God then life is anything but peaceful and settled.  I am so thankful for my God and my Savior for making a way for any one who desires to know God will find HIm.