Your Beliefs And Values
What do you stand for? (should mirror desired outcome)
Mine as an example:
MY training systems along with strongman training is the BEST for developing strength / power athletes.
In order to improve and get REAL results you have to TRAIN HARD (we never use the word "workout")
I HATE fitness gyms and lies about fitness (Our tag line is NO GIMMICKS, NO BS, NO FRILLS JUST HARD WORK)
Principles: character, food, body, service, faith.
You can see in the message I deliver who I'm trying to target. The average "200lb soccer mom" as stormshadow put it, will more than likely be turned off by my message, but the athlete or the "weekend warrior" who still plays hard on some club team might appeal to this along with high school coaches who want their team to train in the offseason like football or anyone male or female to isn't afraid of a challenge and wants to work hard.
Develop your message to suit YOU. JNN mentioned that he was a "Trophy" trainer, IMO that's a great angle as long as your honest with your clients and your training methods work.