Believe In What you're Doing says Aaron Pascoes:

If you do not believe your business then why would your customers believe it? consider a boy who has always wanted to be a choreographer and he's forced to check engineering science.

He will never be good at being an engineer because his interest lies in creating and directing professional dancers. The same is that the case with business. So always chose to own a business that has your interest in it. Then take it seriously.