Sunshine just means that the flowers are brilliant and can't live up to it.

: While the sun is just right now, while the breeze is blowing, it is quiet and comfortable, and while bloom is in full bloom, it is not the time to ruin the flowers.

The extended meaning is: cherish the good times now, cherish the present, seize the opportunity and don't miss it.

This sentence is often used to encourage and motivate injured people to move forward, and also to advise everyone to cherish time.