Well--one thing I'm really finding helpful is Is 55 :8 and 9---For my thoughts are not your thoughts, neither are your ways My ways, declares the LORD. For as the heavens are higher than the earth, so are My ways higher than your ways, and My thoughts than your thoughts."
It is sometimes so helpful for me to focus on this. It is easy to get discouraged especially about other people ....but God is God and He works the way it is best to work in them. It is hard when you see someone that may not be happy and it can be a simple thing of attitude. I have really seen the importance of controlling thought life and using Philippians 4 :8 as a filter--whatever is true, honorable, right, pure, lovely, good repute, excellence--anything worthy of praise---that is what my mind needs to dwell or ponder on. This has to apply to me and my thoughts of others--trusting God to love and work in them at his rate which is of course the right rate!! He knows what He has to teach them and how.