hummm well... in "modern Danish" it is indeed very common to use "please", but yes, I do agree that there is no need for keeping the English word in this sentence.
I would, however, change it to:
Hvorfor er livet så svært? Vær sød at give mig et svar.
Det havde jeg tænkt på først. Kan kun være enig med dig. Oh, sorry, forgot to write in English. I agree completely with you. Can you change it, please Anita, and thanks.