Keep your heart!
"Keep your heart with all diligence; for out of it are the issues of life." Proverbs 4:23
The 'heart' is here put for our whole inner being. It is that which controls and gives character to all that we do.
To 'keep' — garrison or guard — the heart is the great work which God has assigned us. The enablement is His — but the duty is ours. We are to keep . . .
the imagination from vanity,
the understanding from error,
the will from perverseness,
the conscience clear of guilt,
the affections from being set on inordinate or evil objects,
the mind from being employed on worthless or vile subjects.
This, this is the work to which God has called us!
"The keeping and right managing of the heart in every condition, is the great business of a Christian's life!" John Flavel