Saying No

About two weeks ago I got a surprisingly email in my inbox. An old friend of mine is about to launch a new startup and he asked me to become the CTO of their new company. My first reaction was: Wow! Since this first email we have talked each other (a colleague of him was involved too) quite a few times. They have a good idea, an already working prototype of the product they want to create and enough money to be alive for a while if things don’t go as expected.