Lifesaver

When people are happy, they don't need it.
When people are safe, they don't need it.

It is used when they need help.
It is used when no one around thme.
It is used, but only for short moment.

When people are safe again, probably they don't need it anymore.
When people are happy again, probably they don't even remember it anymore.

Perhaps, I am just like that lifesaver.