The Tur (Orach Chaim 24) writes, "One isn't obligated to buy a four-cornered garment to be obligated to put on tzitzis, but if one wants to wear a four-cornered garment, he must put tzitzis on the corners. Still, it’s good and proper for everyone to pursue the mitzvah of tzitzis, to wear a four-cornered garment with tzitzis on them, so he can wear it all day. For the primary point of tzitzis is to remind us to keep all the mitzvos, and this is something one needs to remember every hour and every moment. This can be compared to one commands his friend to do something, so he ties a knot on his belt to remember. Tzitzis have five knots, corresponding to the five books of the Torah, and four corners, so to whichever side he turns, he will remember." Similarly, the Sma'k writes, "Although the verse doesn’t seem to obligate one to buy a four cornered garment, it seems that it’s a great mitzvah to buy one, to remember the Creator's mitzvos…" The Alshich HaKadosh writes, "One might ask, 'How can you tell me that by looking at the tzitzis I will remember to do all the mitzvos? Behold I wear tzitzis every day, I see the tzitzis, and I'm not remembering to keep all the mitzvos!' … We can answer this question with a mashal: When people want to remember something, they tie a string around a finger, so they can see it and remember what they have to remember. [The string will only help if they think about the matter they want to remember when they look at the string.] However, if a person ties a string around his finger every day [because he heard that this is helpful for one's memory, but he doesn’t] think about anything particular to remember, then, when the day comes that he wanted to remember something, but he forgets, he will say, 'How did I forget? I have a string around my finger? It must be that the string around my finger doesn’t help!' Wise people will tell him… 'Fool, since you didn’t think about what the string should remind you, how could it remind you?' The same is with regards to our subject. Hashem says, 'I know that you are going to tell me that you wear tzitzis, but it isn't helping you to remember the mitzvos. Therefore, I am going to make you aware that if you will make the tzitzis to look at them and to remember the mitzvos, the tzitzis will help you remember the mitzvos, like a person who ties a string around his finger... However, if you are going to wear the tzitzis by rote, without intending to look at them and to remember the mitzvos, then surely when you look at the tzitzis you won't remember Hashem's mitzvos. This is the intention of the verse, your intention should be to look at the tzitzis and to remember, and then by looking at the tzitzis, you will remember to do all of Hashem's mitzvos. Whereas, if you don’t intend to remember, how could it remind you…" The tzitzis are a symbol of our submission to Hashem. Years ago, a slave owner would brand his slaves to identify himself as the owner. The tzitzis is like a seal and symbol signifying that we are Hashem's slaves.
The Or HaChaim HaKadosh quotes this Tosfos, and elaborates: "When you will look at the sign of your slavery, you will take heart that you aren't free to do as you want with your food, clothing, speech, and all your deeds, like a slave who is afraid of his master. You will stand when your master tells you to stand, and you will do all the tasks Hashem commands you to do…"
The Sefer HaChinuch (mitzvah 387) elaborates on the mitzvah, "Don’t stray after your heart and after your eyes," explaining that there are two parts to this prohibition: "The concept is that one shouldn’t think thoughts that counter the foundations of the Torah because one may come to heresy. If a [heretic] thought comes to your mind, stop thinking about it, change your thoughts, and think about the true and good Torah. Similarly, one shouldn’t pursue what his eyes see. Included in this commandment is not to pursue physical temptations… This is referring to heresy and adultery… The reason for the mitzvah is clear: by guarding your thoughts you will be safeguarded from sins your entire life. This mitzvah is a great foundation of our religion, for bad thoughts are the "fathers of impurity," the root of sin… Know and repeat often, that which Chazal say (Avos 4:5), 'One sin brings on another sin, and one mitzvah brings more mitzvos.' If you will satisfy temptation once, you will desire them many more times. But if you will be a warrior and conquer your yetzer hara and turn your eyes from seeing evil one time, it will be easy for you to do so several times. Temptation draws a person like wine draws an alcoholic. Those who drink wine are never satisfied, they crave it passionately… If they would drink a cup of water the temptation for wine would be silenced, and it will be good for them. Similarly, the yetzer hara becomes strengthened with whatever a person is accustomed to. When they refrain they will be happy with their lot all day long…"
One of the tzaddikim said that a lack of peace of mind is never an excuse not to study Torah, because Torah study generates peace of mind. Many people find learning Torah difficult for various reasons, but this shouldn’t deter a person from learning Torah. The difficulties make Torah study special. The Gemara says, "The reward of a Torah class is the pushing" (Brachos 6).13 The Chidushei HaRim zt’l explains that the Gemara is saying, "The primary reward for studying Torah is the hardship involved." Sometimes it’s easy to study Torah, but the primary reward will be received for when it was difficult and you studied regardless. The Chidushei HaRim said, "It’s possible that the galus (exile) is so long because Hashem loves Torah mitoch hadchak (Torah studied in poverty and from amidst hardships)."
Someone said to the Beis Yisrael (of Gur), “A kabbalist told me that I’m suffering from an ayin hara.” The Rebbe replied, “Most of the world suffers from an ayin hara. As the Gemara (Bava Metzia 107) says, ‘Rav entered the cemetery and said, ‘Ninety-nine people die from an ayin hara, and only one person dies a natural death.’” The Beis Yisrael’s intention was that in addition to the ‘evil eye’ that harms people, most people (ninety-nine percent) aren’t as careful as they should be with their eyes. When one will guard his eyes, he will be protected from the ayin hara.
When a chassan says a dvar Torah (at a sheva brachos, for example) people customarily start to sing and interrupt him. Why? The Chidushei HaRim said that this is to teach the chassan that he should continue learning Torah even amidst disturbances.
Rebbe Yissacher Dov of Belz zt’l was once in Vienna, and was impressed with a certain bachur who was learning Torah with a geshmak for several hours, throughout the Shabbos. Rebbe Yissacher Dov wanted to find out more about this exceptional bachur, so he spoke with him. The bachur said, "I was drafted into the army. Generally, soldiers are forced to desecrate Shabbos. I spoke with the head of my platoon, and requested that he give me Shabbos off. In exchange, I told him that I would work longer hours throughout the week. It was a miracle that he agreed to my request. I decided that I should repay Hashem for the miracle, and therefore, I try to make the entire Shabbos holy to Hashem, immersed in Torah." When Rebbe Yissacher Dov repeated this, he added, "Who knows if his Torah isn't preventing the building of the Beis HaMikdash? Because Hashem has immense pleasure when one studies Torah with mesirus nefesh." The opportunity to make a nachas ruach for Hashem is available for us as well. If we will study Torah, even when it is hard, even when we don’t want to, it will be considered toiling in Torah, and Torah with hardships is so precious to Hashem. The Torah will be engraved on our souls, purify us, and elevate us.