“For everything there is an appointed time,
and an appropriate time for every activity on earth:
A time to be born, and a time to die;
a time to plant, and a time to uproot what was planted;”
Solomon apparently believed there is a fixed order of events determined by God. Humans are not independent of God. Just as he set the heavenly lights to determine seasons and years, so he determines the times for human activities.
If there is an appointed time to die, and that appointed time is not known to us, then now is the appropriate time to prepare for the moment of death.