One idea for specialisation is to focus on bikes and riding. Perform exercises that you understand will be good for cyclists ( you may even want to do indoor cycling classes) and make sure to do several sessions of biking in some good areas that will be safe and enjoyable ( stay off the road for safety).
Most people either cannot afford a decent bike, have no room for one or would rather not buy one one remix you can do to add value to your pt service is to offer bike rentals as an additional upsell or included in your session price, this is not a new idea - many hotels offer a bike rental service if they are by the coast or country area if not you can usually find a bike rental shop in the vicinity this is just offering a fitness 'spin' on an old idea.
4 SAVADECK DECK6.0 Carbon Mountain Bike