Meaning/Usage: To express nothing else is important

Explanation: Usually used before expressing what is actually important. The below example sentences will illustrate this.

"Nothing matters more than being happy."
"Don't worry about what she said. Nothing matters but what you think."
"Nothing matters if we can't start getting along better."

A. "My husband told me I need to make a decision about getting a job."
B. "Nothing matters but you being happy with what you are doing."
A. "You are right. I will need to find something I love to do."
B. "Good luck."

Other Common Sentences

"Nothing else is important at this time."