The following incident occurred over a hundred years ago when one of the great Rabbis was travelling to Jewish communities to collect donations for his yeshiva.
 

One night during his journey, while the Rabbi was staying at an inn, he woke up feeling extremely thirsty. His student, who was escorting him, also woke up and saw the Rabbi get up and walk towards the spot where the innkeeper's water barrel was.
 

The student accompanied him, but to his surprise, when the Rabbi reached the water barrel, he turned around and returned to his bed. The following morning, after praying and eating pat shacharit (breakfast), the student asked his Rabbi to explain the incident of the preceding night: why did he take the trouble to walk all the way to the water barrel, but when he reached it he didn't drink even one drop?
 

The Rabbi answered: when I woke up and felt thirsty, I deliberated what to do: whether to overcome my yetzer (inclination) and not go to drink, or that maybe this is only laziness disguised in the rationalization of overcoming the yetzer?
 

I decided not to be lazy, so I got up and went over to the water barrel, and when I reached it I didn't drink, in order to prove to myself that it is possible to overcome the yetzer if one really wants to.
 

In our parsha, the Torah commands the nazir not to drink wine and not to cut his hair.
 

The commentators explain that these two issues represent self-restraint from the temptations of this world:

Wine represents the debauchery and loss of self-control which is caused by indulging in the desires of food and drink, and hair represents physical beauty which most people are enslaved to all their lives. 
 

And the question arises: understandably, the prohibition of drinking wine represents forbearance from superfluous eating and drinking. However regarding hair, to the contrary – we would have expected the Torah to command the nazir to shave his head every day of his period of nezirut in order to emphasize that we must not be led by superficial beauty. So why is he specifically commanded to let his hair grow and not to cut it?
 

Perhaps we can answer: indeed the nazir lets his hair grow, but at the end of his nezirut he is commanded to cut off all the beautiful hair he grew and to burn it. Exactly at the end of his days of nezirut, the nazir is required to demonstrate that he understands that beauty in and of itself is worthless unless it is l'shem shamayim (for the service of Heaven).

Conceivably the Torah wants to teach us two paths in one's avodat hamiddot (working on character traits).
 

One way is by completely avoiding anything that can lead a person astray, as exemplified by the nazir abstaining from drinking wine.
 

The second way comes to teach us that even when one utilizes worldly things, occasionally at the conclusion he must demonstrate that it was all l'shem shamayim and not for his personal, private benefit.
 

May we merit to direct all of our deeds, speech and thoughts l'shem shamayim, and through this, His blessed Name will be sanctified in the world, and Israel's prominence will reach great heights.