'Diligent' in the Bible

But take diligent heed to do the commandment and the law, which Moses the servant of the LORD charged you, to love the LORD your God, and to walk in all his ways, and to keep his commandments, and to cleave unto him, and to serve him with all your heart and with all your soul.

So be very diligent to love the Lord your God for your own well-being.