Entrepreneur
I want to invent something cool.
Square, Airbnb, Evernote
You get too passionate about your product. Any praise sends you to 7th heaven, and a criticism is like being stabbed
Giving up.
1) Do something you really like: you'll be spending all your time on this and there will be no other rewards for a while
2) Know your customers well. Ideally you have been in their shoes before
3) Nothing can prepare you for the emotional rollercoaster (and the 2nd time is even worse). So it's essential to be prepared for all the rest!