English to German Bus/Financial Business/Commerce (general) tips for success in life

Life is difficult. Thank God it is so. (Fußnote:) Or whoever or whatever you choose so to thank. Don´t write it in.
There is a statistic that suggests that for a lot of men, retirement is a really bad idea. Lots of them die within a relatively short time of handing in their briefcase. (Fußnote:) I don´t know if this affects women just as adversely. You may write in.

Zweimal diese Fußnote mit "write in". Was bedeutet das Wort hier? Danke im voraus.