Message From the Imam: Optimism
In the day of Hudaibiah, when the prophet (pbuh) came to perform Umrah in Makkah, many messengers of Quraish were sent to negotiate a deal with the prophet (pbuh). When Suhayl, the son of Amr, came, the prophet (pbuh) said, “Ease for your matter has come.” (Hadith narrated by Bukhari.) He (pbuh) saw ease in the name of Suhayl which in Arabic means "ease and joy." The prophet (pbuh) was optimistic and hoping for something good to happen, and he saw the sign in Suhayl’s name.
Optimism is based on the positive feeling about how Allah will treat you in this life and in the Day of Judgment. The prophet 
(pbuh) said in the holy Hadith that Allah said: (Allah) "I am where my servant assumes of me." (Hadith narrated by Bukhari.) The more you have trust and faith in Allah’s mercy and forgiveness the better chance you have to enjoy it. The prophet (pbuh) also said, "The positive assumption of Allah is in the excellence of worshiping Allah." (Hadith narrated by Ibn Adii.) This positive feeling is connected to how much you really know of your Lord! The more you know about Allah the more you trust in Him, and the more you trust in Him the more optimistic you are.
When you know that Allah is Al A’dle (All Just), you rest with all matters of life, for all that happens is fair.
When you know that Allah is Al Hakeem (All Wisdom), you gain patience, for everything will prevail in truth even after a period of time.
When you know that Allah is Al Waliie (Patron), you feel safe even if all waves of hardships are shaking you in fear.
When Adii Ibn Hatem saw how Muslims were weak and vulnerable, the prophet (pbuh) said, "Probably O Adii, what prevents you from entering this religion is what you see of their necessity! By Allah, money is almost to be immersed among them until no one will be found to take it! And probably what prevents you from entering in it (Islam) is what you see of their enemy’s large number and their little number! By Allah, you will almost hear of a woman leaving from Qadisiyyah on her camel until she visits this House (Kaabah) with no fear! And probably what prevents you from entering it (Islam) is that you see the dominion and authority in others! By Allah, you are about to hear the white castles in the land of Babel is opened to them (under their control). Adii said: ‘So I accepted Islam’. (Hadith narrated by Ibn Katheer.) In this Hadith we can see how the prophet (pbuh) was optimistic about the future of Islam even during times of hardships.
In Islam there is no place for pessimism. The prophet (pbuh) said, "(There is) no (place for) pessimism and I like the (Fa’le, righteous optimism). They said: and what is the Fa’le O prophet of Allah? He said: The nice word, the gentle word." (Hadith narrated by Bukhari.) A good example of this issue would be the type of words you choose when visiting someone who is ill. Even if you know this person’s illness is terminal, you should still use good, gentle and optimistic words of hope. The prophet (pbuh) said, "If you entered to an ill (person) breathe (using optimistic words) for him in (Ajal; appointed term of death); although it does not prevent things (of fate) but it soothes the sick’s soul. Hadith narrated by Ibn Majah and Tirmizi.
The prophet (pbuh) spoke of the liability of those who are pessimistic. "If a person says people are perished then he is the most perished of them." Hadith narrated by Imam Muslim.
Being optimistic helps you stay strong. It was narrated that when Imam Ibn Taymiyah was in prison at the time of Tatar, he would say to his students, "You shall be victorious." His students would say, "Say insha Allah O imam!" He would answer, "I say insha Allah in assurance (تحقيقا) not in possibility (تعليقا)." He meant the phrase 'insha Allah' can be used to refer to what you do not know of the future or to what is known for certain because of whatever Allah has set as a way that will prevail.
This was seen also in the words of Moses (Musa) when the companions of Moses said: {فلما تراءا {الجمعان قال أصحاب موسى إنا لمدركون قال كلا إن معي ربي سيهدين {then when the two multitudes saw each other, Moses’ companion said: Indeed, we are, most surely [doomed to be] overtaken! He said: No, indeed! Most surely, my Lord is with me. He will guide me.} 26:63
Being optimistic helps you repent. Satan will always use the sins that you have committed to drag you into more sins as he tries to convince you to give up and to be hopeless. Allah urged people whenever they fall into sin to be optimistic and see Allah’s door is open for mercy and forgiveness. He said: {قل يا عبادي الذين أسرفوا على أنفسهم لا تقنطوا من رحمة الله إن الله يغفر الذنوب جميعا} {Say [O prophet: God declares to humanity]: O my servants! Those [of you], who have committed [sins in great] excess against their own souls; never despond of the mercy of God! For, indeed, God forgives sins, one and all.} 39:53
In case someone felt pessimistic; this is what the prophet (pbuh) advised:
1. The prophet (pbuh) said, "In the believer are three characteristics, for each habit he has an exit out from it. Pessimism, envy and bad assumptions. His way out of pessimism is not to halt him [from doing things], and his way out of bad assumptions is not to verify, and his way out of envy is not to transgress." (Hadith narrated by Baghawi.)
2. You should rush to Dua when you feel pessimistic. The prophet (pbuh) said, "If someone saw what he hates let him say: O Allah no good deeds will be brought but by You and no harm will be prevented but by You and no power or strength only through You." (Hadith narrated by Abu Daoud.)