Fallacy : What's there to be worried about the future? What does the future holds? What does it resemble? What can it change?
Answer : The future holds our lives. The future changes us today.
Fallacy : Why do people regret?
Answer : Regrets are a form of self-punishment for unacceptable things that happen beyond our control.
Correction : We go on. We do not have regrets.
Fallacy : He / She doesn't care.
Answer : We have Allah.
p/s : sadness and happiness hold no difference; Allah is there to guide us.