It may help to be a little more specific about your question, but I assume you have a client who is already in good physical condition. What are your client’s specific goals? It could be that your client wants to take his/her fitness to the next level–so I would find out in detail what those goals are (reduce body fat percentage, create more definition in certain areas, gain strength, etc…).
What I’ve found from training individuals over the years is that even though we see a fit individual, that client may want to take their fitness to the next level. Either we can accommodate that goal, or we may need to refer to another trainer who is more specialized. Either way, being fit means many things to different people, and everyone has different goals–it’s very personal and relative to each individual and their body type.
The more specific his/her goals are, the better off you will be to help that client achieve them.