"My day is ruined!"
Ever hear someone say that, or say it yourself?
No.Your day isn't ruined. You ruined your day.
Your day is entirely in your control. It is all in how you act, think about things, and understand them.
There are two things that can ruin your day: your ignorance or underestimation of Allah, subhaana wa ta'ala and your sins (which includes any disobedience to Allah or doing things He dislikes).
What about if someone is unpleasant to you, with no wrongdoing or provocation on your part? Can't that ruin your day? Not if you know that Allah is Al-Hakeem (The All-Wise), As-Samee' (The All-Hearing), Al-Baseer (The All-Seeing), Al-Haseeb (The Reckoner), Al-Hakam (The Judge), and Al-Adl (The Just). In such a case, the one who harmed you has given you a gift; either they have given you some of their good deeds or taken some of your sins - a perfectly good deal. Sit calm and say alhamdul'Illah.
What about if you fall sick, are hurt, or suffer some difficult test? Can't that ruin your day? Not if you know that Allah is Al-Wudood (The Loving), Al Hafeedth (The Guardian), Al-Wakeel (The Disposer of Affairs), Al-Qabid (The Taker) and Al-Baasit (The Extender). In such a case, you know that Allah loves you and is reminding you to return to Him in repentance and prayer. He is expiating your sins, elevating your ranks in Jennah, and guiding you call on Him, alone, for help.
What about if your children behave as though they never learned manners, respect, or morals? Can't that ruin your day? Not if you know that Allah is As-Salaam (The Peace), Al-Qawiyy (The Strong), Al-Mateen (The Powerful), Al-Jabbaar (The Compeller), Al-Musawwir (The Shaper), Al-Mujeeb (The Answerer), Al-Haadi (The Director), Ar-Rasheed (The Guide). Throw your hands up in du'a and keep on doing what your doing to guide them to righteousness. Leave the rest to Allah's Perfect Plan.
What if you are feeling unappreciated? Can't that ruin your day? Not if you know that Allah is Ash-Shaakir (The Recognizer and Rewarder of good) and Ash-Shakoor (The Appreciative). and Al-Kaafi (The Sufficient). Why worry when the only One Who can recompense and reward is appreciating you?
But what about if you commit a major sin? Can't that ruin your day? Yes, it can, if you don't repent for it with sincerity and heartfelt regret. Even with a complete and true repentance it can cast a shadow on your day. However, for the true believer the answer is still no, because you know that Allah is At-Tawwaab (The Oft-Returning), Al-Afuww (The Pardoning), Al-Ghafoor (The Forgiving), Al-Ghaffaar (The All-Forgiving), and Ar-Raheem (The All-Merciful). He created us to err and turn to Him in repentance, thereby learning a lesson and not wanting to commit that sin again. Crying to Allah in sorrow, regret, and repentance is an excellent thing. It confirms that you have eemaan and taqwa - hardly something to ruin your day. More like something to give you hope and something to build on, maashaa Allah.
So, I say to you, if you have correct understanding of Allah, your Creator, and true taqwa and eemaan, then nothing and nobody can ruin your day - not ever.
Resources: The Explanation of The Beautiful and Perfect Names of Allah (subhaana wa ta'ala) by Abdur-Rahman bin Nasir as-Sadi (raheemahUllaah)