Each believer in Christ Jesus will have the opportunity to develop strategies to overcome the onslaught of the enemy. The enemy will try continually to move the believer out of faith. Murmuring and complaining stem from a heart issue of dissatisfaction. We can choose to believe that the Lord will alleviate the situation in due time or we will find ourselves embittered in the "wrong" spirit. 

Psalm 27:13 King James Version (KJV)

13 I had fainted, unless I had believed to see the goodness of the Lord in the land of the living.