In her book titled "New Coaching Manifesto", The Whole Truth About Coaching Business -- Why only 9% of coaches succeed while all the rest fail, and what you must do to prosper in coaching, Milana Leshinsky talks about developing your coaching business instead of a coaching practice.
The difference between a business and a practice is that the income attached to practice is directly proportional to your involvement. When you stop working due to retirement, vacation, being involved in an accident or just getting sick, your income and the value of your business almost instantaneously drops down to near zero because you are essentially it's only asset.
On the other hand, building a business not only requires you to develop residual and passive forms of income, it also requires you to diversify your activities which will have the side benefit of also keeping your life as a coach interesting.
A free eBook version of Milana's book can be downloaded from her web site at www.coachingmillions.com. Even if you are not interested in reading the 35 page book, at the very least you should take a look at her web site and discover the free wealth of information and ideas for building a sustainable coaching business.