“Keep your mind on God, and keep busy at something useful and profitable for others. You will then always be happy and at peace. You’ll have no time for fancied offenses, or self-pity, or criticism of others, or catering to your own lusts and desires. Wasted time or self-indulgent time is unfaithful stewardship and self-destruction. God has set it up that way, and it is wisdom, and we are very foolish to think we can outwit Him, and find happiness and satisfaction any other way” (GVG).

http://www.christadelphianbooks.org/agora/comm/20_prov/prov17.html