at peace with (something/yourself)

feeling calm and relaxed about something or yourself.

He appears to be at peace with the world these days.

These are good times for Randy, a man at peace with himself and his career.

• on a silver platter
• on a slippery slope
• on a tangent
• on automatic pilot
• on a wing and a prayer
• on back
• on balance
• on behalf of
• on behalf of someone
• on bended knee
• on bended knees
• on best behavior
• on blocks
• on board
• on borrowed time
• on call
• on case
• once again
• once and for all
• Once bitten, twice shy.
• once in a blue moon
• once-in-a-lifetime
• once in a lifetime
• once in a while
• once upon a time