Decree

Go easy on yourself, for the outcome of all affairs is determined by Allah’s decree. If something is meant to go elsewhere, it will never come your way, but if it is yours by destiny, from you it cannot flee – Umar bin al Khattab [Radi-Allahu anhu]

Destiny- Do not despair

Not feeling disappointment for any thing that happens throughout the course of this life is a mark of a true understanding of the meaning of faith. Failure to see good in things that happen, being fraught with constant fear, anxiety, despair, sorrow, sentimentalism, on the other hand, indicate a lack of pure faith. This confusion must be removed promptly, and the joy emanating from unswerving faith must be accepted as a necessary part of life. A believer knows that events that might at first sight appear unfavorable, including those which he caused to happen by committing an error, will ultimately turn out beneficially for him. When he uses the words "adversity", "misfortune" or "if only...", it is only to draw a lesson from an experience. In other words, the faithful knows that there is good in whatever happens; he learns from his mistakes and seeks to correct them. However, if he were to fall into the same error again, he keeps in mind that it is all for a specific purpose, and simply resolves to "conduct himself more correctly the next time." Moreover, even if the same thing were to occur dozens of times over, a Muslim must keep in mind that ultimately it is for some good; such is the immutable law of Allah.

What is Destiny? by Harun Yahya

Destiny is Allah's perfect knowledge of all events past or future, as if a single moment. This expresses the absolute sovereignty of Allah over all beings and events. People can be aware of a certain event when they experience it. But Allah knows all events prior to their occurrence. For Allah, past, present and future are all the same. They are all within the knowledge of Allah since He is the One Who creates them.
Every event a person sees, and every noise he hears, are in ever instance part of a life that has been created for him as a unit. Whether major or insignificant, no event in the universe happens by coincidence. No flower either blooms or fades by chance. No man comes into existence or dies out of pure coincidence. No man becomes sick by mistake, and neither does his sickness develop in an uncontrolled manner. In each case, these occurrences are especially predestined by Allah, from the very moment they were created.