There is no reason why a private gym should be any less stylish than your gourmet kitchen or luxurious bathroom. Once you have taken care of the basics such as the size of the room, ceiling height, flooring and ventilation then what remains is to establish that elusive point of intersection between functional and aesthetic compatibility.
The following images might just help. By showcasing gymnasiums belonging to others you maybe able to use their ideas -in combination with your own-to create your own personal statement of fitness and style.
Gyms don't have to be land based. Some of the most stunning and inspirational gyms are on some of the most beautiful super yachts. When money is no object the sky is the limit. Not all of us can aspire to this kind of luxury but there is no reason why some of their exquisite design ideas cannot be replicated. All that is required is imagination.