You in real estate all that matters is LOCATION, LOCATION, LOCATION! For running a business and getting a lot of clients without much work – the most important thing it will come down to is SEO, SEO, SEO. So make it easy on yourself by getting a name that reflects your location if you’re going to have a brick and mortar place or have people in the area find you.
Example: if you live in Pawnee, Indiana. I’d try to find a domain name that reads: PawneePersonalTraining.com (this will help you rank higher in google, especially if you have a website with great content. Basically, your key words, “trainer, fitness trainer, personal training, etc. then add your city/target area to the end of those keywords. Good luck!