An interesting trend we have seen over the last five or so years is that a fairly large number of automotive repair businesses just cease to exist at some point. We see this when we get magazines returned or cancelled. Whilst there are many reasons for this, a very common one seems to be that the owner has reached retirement age and has managed the business down and is just shutting the doors as they can not find a buyer.
The face of the repair industry is changing, which may mean your business needs to change premises, change focus and adapt. Going back to the 70’s, a significant number of repair shops included fuel retailing. The fuel was a useful sideline but the workshop was the main part of the business. Now very few fuel sites also have workshops. This is mainly as the number of fuel sites has decreased, the size and area required for fuel and the associated retail area has increased, consuming any space for servicing. This means that all the service businesses that used to be there needed to either close down or move to a new location. 
It is a key part of business to constantly monitor your situation and plan ahead. A key part of this is succession planning; if you own the business, can you groom one of your staff to eventually take over the business. Maybe this could be gradual with them starting out with a part ownership stake which gradually increases as you approach retirement, allowing you to ease out of the business with reduced hours rather than making a sudden cut. None of this happens without planning, which needs to start 10-15 years earlier, otherwise your business might end up being one of those where the owner locks the doors and walks away when they retire.