Saying no is an important life skill, as is saying yes. Saying no should be used wisely. Pray daily for guidance in making decisions, generally, and in these specific situations. I often say, let me look at my schedule and I will get back to you; then I take time to think about it seriously, sometimes praying just for help with that decision, then I get back to the person as soon as I can. I have found that when I can consider it, even for a few minutes, I usually can make an informed decision. If it is no, let them know in a kind way and move on. -Rob Dunn