We all end up doing what we do well and what we can be paid to do - because that is the easiest thing to do. We know how to do the work and we get paid for it so the rewards are instantaneous. But can we do this day in and day out for the rest of our lives - the answer is no because its not what we want to do. The passion will be lacking. When there is no passion there is no yearning to be the best or to give quality or to go to all lengths to ensure that the customer is delighted. When this does not happen you will start to lose customers and the business will not sustain.
It is important to focus on ideas that you want to work on and are excited to work on and then hope that it all comes together by becoming an idea that you are very good at doing and a customer is willing to pay you for doing it. Hitting this sweet spot happens over time and significant effort.