In this life we are diligent in many things which is good, but first and foremost we must be diligent in our faith in God (Hebrews 11:6) But without faith it is impossible to please him: for he that cometh to God must believe that he is, and that he is a rewarder of them that diligently seek him.
The book of proverbs teaches us the sage advice to keep the word of God always, and to diligently keep our heart set on the word which is our life! (Proverbs 4:20-27) My son, attend to my words; incline thine ear unto my sayings. Let them not depart from thine eyes; keep them in the midst of thine heart. For they are life unto those that find them, and health to all their flesh. Keep thy heart with all diligence; for out of it are the issues of life. Put away from thee a froward mouth, and perverse lips put far from thee. Let thine eyes look right on, and let thine eyelids look straight before thee. Ponder the path of thy feet, and let all thy ways be established. Turn not to the right hand nor to the left: remove thy foot from evil.
By the choice of not being diligent in keeping Gods will in our life we only trouble our own house (Proverbs 11:27-31) He that diligently seeketh good procureth favour: but he that seeketh mischief, it shall come unto him. He that trusteth in his riches shall fall: but the righteous shall flourish as a branch. He that troubleth his own house shall inherit the wind: and the fool shall be servant to the wise of heart. The fruit of the righteous is a tree of life; and he that winneth souls is wise. Behold, the righteous shall be recompensed in the earth: much more the wicked and the sinner.
Joshua knew the importance of keeping the commandment’s of God, and when the eastern tribes returned home he instructed them to be diligent in keeping the law of God and His commandment’s as Moses taught (Joshua 22:4,5) And now the LORD your God hath given rest unto your brethren, as he promised them: therefore now return ye, and get you unto your tents, and unto the land of your possession, which Moses the servant of the LORD gave you on the other side Jordan. 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.