This is by far one of the best prayers ever.  So intense, that I tend to read this every time I feel frustrated [which has been quite a few times recently 🙂 ] 

Why do you worry ? Why are you scared ?
Whatever happened, it happened for good.
What is happening, is also happening for good.
Whatever will happen, that too will be for good.
What have you lost for which you weep?
What did you bring with you, which you have lost?
What did you produce, which has perished?
You did not bring anything when you were born.
Whatever you have, you have received from Him.
Whatever you will give, you will give to Him.
You came empty handed and you will go the same way.
Don’t be remorseful about the past , nor worry about the future. The present is before you .
What is yours today was someone else’s yesterday and It would be someone else’s the day after. You may think all of yours is for you to keep. This is the main cause of the sorrow.
Change is the nature of life. Remove the thought "Mine and yours" and "Little and big" from your mind. Then everything is yours and you belong to everyone.
Then what are you? surrender yourself to the higher power, the only source of your strength.
He who realizes this will be free from fear, worry and emotion.