It is hard to dial your wisdom down to one lesson at first blush.  One thing that I am sure of is that our beliefs evolve through each decade and life experience that we are blessed to share in our brief time here on Earth.  Upon further thought, the one thing that I know regarding Faith is a constant.  I believe that all of our best is experienced through focusing on love.  If we don't attempt to approach everything, and I do mean everything, through the lens of love then one is not acting in true Faith.

Jesus teaches us that we should love our neighbor as we love ourselves.  By our neighbor He means our family, our friends, our boss and coworkers.  He means the person that shows us support as well as the person who wrongs us (in our perceptions).  If we can approach all of our daily duties with love in our hearts and empathy in our eyes, we can live life on a higher level.  If we can feel love and compassion for all of God's creations than we can be at peace.  I believe that if we base our days in such a manner then rest we can turn over to God as the Serenity Prayer suggests:

God grant me the Serenity to accept the things that I cannot change.

The Courage to change the things that I can.

And the Wisdom to know the Difference.

Thy will, not my will, be done.