Biblical hero Samson had immense physical strength. What was the secret to his superhuman strength?

In the Hebrew Bible, Samson - (Hebrew: "man of the sun") was the last of the judges of the ancient Israelites. The biblical account states that Samson was a Nazirite, and that he was given immense strength to aid him against his enemies and allow him to perform superhuman feats, including slaying a lion with his bare hands and massacring an entire army of Philistines using only the jawbone of a donkey. However, if Samson's long hair were cut, then his Nazirite vow would be violated and he would lose his strength.

Samson is betrayed by his lover Delilah, who, sent by the Philistines officials to entice him orders a servant to cut his hair while he is sleeping and turns him over to his Philistine enemies, who gouge out his eyes and force him to grind grain in a mill at Gaza. While there, his hair begins to grow again.