Your behavior and attitude towards the business act as role model behavior for your family. Therefore, speaking and showing positive feelings regarding the business is the best way to motivate the family to join.
Express how much you enjoy it, the exciting and wonderful career opportunities and prospects for growth. Expose your family to managers, employees, vendors and industry colleagues who feel the same way. Excitement breeds excitement, so be a role model for enthusiasm and speak well of everything you do, everyone you work with and the experiences you have.
However, if everyone around you knows the business is killing you, don’t be a phony. If you have spent a career talking about how the business is a dead-end grind, don’t presume you can do a u-turn on attitude, because it will not work. Your family will not take you seriously and your credibility will be tanked. In this type of situation, genuinely express how the business did not work for you because of your personality or love for some other vocation. If the business is suitable to your family, make the case as to why it would be far more compatible to their goals, personality and/or interests.