Creator of the world, watches over everyone individually...

7 Adar II, 5717 (1957)

I received your letter of the 5th of Adar I.

With regard to the inclination toward a feeling of sadness, a good remedy for it is to have it firmly engraved on your mind that G-d, the Creator of the world, watches over everyone individually and, being the Essence of goodness, there is therefore no room for sadness or worry, as has been explained at length in various parts of the Tanya (see Index). It would especially be good for you to learn by heart from the beginning of Chapter 41 (on page 56) until the next page second line; when ever you feel sad or depressed you should review that section in your mind or recite it orally to dispel the unwelcome feeling.
With regard to the question of a beard, since, as you write, you spend most of the day in the yeshivah [Jewish school], it would be the right thing to let it grow. In addition to all the reasons you mention in your letter, there is one fundamental reason in accordance with the Tzemach Tzedek [Rabbi Menachem Mendel, the third Rebbe of Chabad-Lubavitch] - Yoreh De'ah, paragraph 93.
It should also be added that when a Jew does something beyond the call of duty, G-d sends extra special blessings, as is explained in the Zohar and also in the commentary of the Tzemach Tzedek on the verse in Psalms, "And He is merciful" (see supplement to Tehillim Yosef Yitzchok HaShalem). May G-d grant that your example will be emulated by your friends at the yeshiva, and thus you will have the additional satisfaction of having been a pioneer for a good cause.
As requested, I will remember you and all those mentioned in your letter when visiting the holy resting place of my father-in-law, of saintly memory, and may G-d grant that you will have good news to report in all of the above and will be successful in your studies and in your conduct, both of which are based on "serve G-d with joy."

14th of Cheshvan, 5736 [1976]

....Your question is surprising, inasmuch as you surely know that one of the basics of our Torah - called Toras Emes because it tells the truth - is that everything happens by Divine Providence. Hence you certainly have your mission in this world, that is to say, you have also been given the ability and capacity to carry it out. For it is logical that G-d would not give one a task which is impossible to carry out. Furthermore, it is possible and necessary to carry out one's mission with joy, as it is written, "Serve G-d with joy"; also for this the necessary capacity has been given.
One of the ways to stimulate such joy is to reflect, first of all, upon the fact that G-d has chosen the Jewish people, and you in particular, to carry out a mission for Him.
Imagine if a human king would come from his city and residence to visit your home and entrust you with a special task how welcome this would be; how much more so in regard to the King of Kings.
Our Sages state that "It is a pleasure, so to speak, for G-d that He has given a commandment and His Will has been done." Surely it is most gratifying to be able to please G-d, especially as G-d has also promised a generous reward both in this world and in the World to Come.
Carrying the illustration a little further, one should consider that in the case of a human king, one can never be certain that the task he assigns is all for good, or that it can be carried out fully, or that he can fully keep his promise of reward. All this, of course, does not apply in the case of a mitzvah [commandment].
It is also clear that when a person goes about his tasks with joy and confidence he is likely to have greater success, and also more likely to overcome any discouragement or difficulty that might arise.
If you reflect on the above in some depth you will surely find a great deal of strength and encouragement, and you will see how easy it is to carry it out without any doubts in this regard.