Not exactly a prayer for ease and peace:

Teach me, O God, so to use all the circumstances of my life today
that they may bring forth in me the fruits of holiness rather than the fruits of sin.
Let me use disappointment as material for patience;
Let me use success as material for thankfulness;
Let me use suspense as material for perseverance;
Let me use danger as material for courage;
Let me use reproach as material for longsuffering;
Let me use praise as material for humility;
Let me use pleasures as material for temperance;
Let me use pains as material for endurance.

- John Baillie