Do not stress over someones reaction when you call in a debt they owe you today, it's time.
For whatever reason, today you need to call in a debt that has not yet been paid to you. This could be a financial debt, it could be someones time, or it could be an emotional debt, but whatever it is, you need it right now. Do not stress over asking for this or the persons reaction, you are owed and you have every right to call this in.