I have been thinking about the reasons we end up saying 'no' to tasks, possibilities, options and opportunities. For me at all boils down to motivation. The motivation is nearly always in the form of energy; time, excitement, fun, money.
This is especially true when applied to software development. With enough energy you can achieve almost anything with software do you have the motivation to achieve those things?
If you find me saying 'no' it is because you are not motivating me to say 'yes'.