When rejecting another person's request, it is easy to be nice and say no. But, other than that, there is another important step you can take to leave a warm and fuzzy feeling with the rejected person.
I just finished reading the book The Power of Slow: 101 Ways to Save Time in Our 24/7 World
by Christine Louise Hohlbaum. It is about personal development and how to handle your most precious resource - time effectively. Most chapters are easy read and the ideas are talked about in a lot of other books already, but, there is one great point that is very inspiring to me, i.e, how to say no to others but still be friends.
The author listed 3 steps to say no politely:
Acknowledge the person's request. Be serious about the other person's request. Acknowledge when a person approaches you with a request by thanking them. For example, when your neighbor asked you to help organize a food drive but you recognized that it is not something you care to do anymore, acknowledge your neighbor for his or her hard work.
In this step, you would address your own limitations. Say, you'd love to participate in this food drive, but you have already committed to something else at this time. Be firm, stand your ground.
Lastly, try to offer alternatives. When people ask you for help, they may not realize someone else who is available could easily take your place. Offering alternative solutions will take care of the person's concern without drawing too much attention to your own lack of involvement. For example, you could tell your neighbor that your friend is interested in the food drive and could help out.
I found that the last step of offering alternatives is what's typically missing in saying no to others. It is not easy to always offer alternative solutions, but if you could, that would make the other person feel that you are more caring.