My transition from coder to salesman.
The idea that the product would just sell itself was far from true. Even though I had a working product and some demo videos, every single person who showed interest in the product would email me before purchasing.
I was initially so bad that I missed the first email. It took me 8 days to respond because I wasn't actively monitoring the emails. At that point, I received no response back and was left wondering what would have happened if I had responded within 24 hours.
The second email to come in only took me 4 hours to respond, and resulted in my first sale @ $99!