As David was the anointed and rightful king but was unrecognized and rejected by the establishment, so Christ right now is the rightful king over mankind but He is unrecognized and rejected by this world. Those who recognized David as king had to be willing to join him in the wilderness, and share in his unpopularity and rejection. Out of that motley bunch of people the mighty men of David emerged and some of their heroic deeds are recorded in 2 Samuel 23. Their feats portray the activities of believers who have made Christ their King. With this in mind, then, it is very easy to see that the actions of David's mighty men on the battlefield contain lessons for us about spiritual warfare.
Spiritual warfare is very draining at times.
Even though others may throw in the towel, great victory comes to Christians who hang tough and don't give up. A beautiful picture of worship is brought before us in the actions of the three mighty men of verses 15 17. David longed for a refreshing drink from the well of his hometown, Bethlehem. The mighty three overcame the enemy and brought the water to David at great personal cost and in spite of overwhelming obstacles. They were not commanded to perform this deed.