I went to a wonderful networking event in Washington DC last week filled with people in established businesses as well as some with start up businesses. Interestingly, I found several entrepreneurs with two businesses. One gentleman with two businesses indicated that he is phasing out one business and is starting in a business he dreamed about for years. Another networker told me she is building a new exciting business and holding on with another business that provides an income while she builds the new business.

Can you have two businesses, or a parallel career? Many people do it and are successful and happy. One colleague is a business consultant and he does charity work as well...another person in selling does weekend church pantry work for the poor. Many people do similar work in a different setting. To do this sort of thing you should plan on what shifts you have to make in your life to arrange such changes. I know a management person who dedicates time to writing a new book.
More examples: A product sales person who is a college lecturer. An office manager who has started a business and has the time to support both activities. An insurance salesperson who runs a networking group.