The goal of sending out the first email to an old client is not to sell them personal training, it's to get a response.
Getting back an old client is a lot easier than finding and selling an entirely new one.
However, emails can come off as solicitous, making it awkward to continue emailing or message back at a later date if the client still isn't ready to come back into the gym.
What I'm about to tell you are the 5 best ways to email an old client, in order. The overarching theme is that the only purpose of your first email is to get them to respond. As such, you don't pitch anything. Instead, use the email to start rebuilding the relationship.
5 ways to email an old client
1. You remember something personal about them: An event, a birthday, an anniversary—anything. Send an email checking in and asking how little Billy's graduation was.
2. You remember something health- or fitness-related that they suffered from. Find a great piece of related information to send to them. Say you came across it and it made you think of them.
3. You can make a connection through somebody else. "I was just talking to so-and-so and your name came up, so I thought I would say hi. If you get a chance, let me know what you're up to. I'd love to catch up."
4. You make a connection via something or some moment that you shared. "I was doing squats today and thought of you. Remember that time when ...?" And follow with asking how they are.
5. A random hello, which is not the worst thing to do either. Send them a message just saying they crossed your mind and you wanted to see how they and their family are doing. Being thought of is a good feeling.
What it comes down to is this: They know you're a personal trainer and probably understand that you've got a hidden objective. No need to spell that out.
The point is to start a conversation. If they respond without asking how you're doing, respond back with another question and keep doing this until they either stop responding or ask how you are. Ask enough questions and their natural response will be to ask you a question too: how you're doing or what you're up to. If you're lucky, they might even mention that they were thinking of coming back into the gym and, "what great timing you have."
At that point, mention that you're loving training clients and happy that you get to help so many people etc. etc. etc. Write with excitement and passion.
If you've lost a relationship, get it back. Step 1 is getting a response to your initial email. Once you do, don't let the relationship fall by the wayside again. When they're ready to come back, you'll be the one they call.