This verse reminds me of what Jesus said in Matt. 6:34b "...Sufficient unto the day is the evil thereof." Each day has varying degrees of 'evil' or 'hardships' (Thayer) or 'mischief' or 'malice' (Strong). JFB suggests "the day of Satan's special assaults in life...". Bad things do happen to good people. And in this verse we as Christians must be prepared to take on life's trials and pressures. Again the way to come out victorious is to put on or to take on the whole armor of God. We may not know what evil today may bring or tomorrow for that matter, but we must be ready to obey God's Word in putting on the whole armor that He has furnished for us.