I’m a 32-year-old private coach… and I really like having affairs with my feminine, midlife shoppers. Their husbands ought to thank me for enhancing their wives (out and in of the bed room!)

I had my first affair with a client four years ago. I’d just started a job as a personal trainer at an exclusive west London gym, and launched an Instagram account to market myself to private clients too.

Lisa worked in TV and was 45. I was 28 at the time and didn’t mind the age gap. Older women know what they want, and generally have a no-strings attitude – which is very sexy.

Many are looking to escape stale marriages and are less emotionally demanding than those my own age.

Lisa had two teen boys, and a husband who was ‘away on business a lot and says I need to lose weight’. Nice chap.

We started going to the local park in Shepherd’s Bush for our workouts. Yes, Lisa was slightly out of shape – she worked from home, which meant she was slumped over a laptop most days – but she was also gorgeous, with long blonde hair.

After our third session, Lisa burst into tears and told me she was having a ‘rough time’ with her husband.

Was it a come-on, or do I look like the kind of guy a woman can confide in? As well as the six pack and the biceps, I have shoulder-length brown hair and don’t act like a typical strict PT.

‘I don’t know what to do. He just ignores me a lot of the time. I feel worthless,’ she told me. We went to a nearby coffee shop, where she leant over and squeezed my arm.

‘How come you’re so empathetic and still single? You’re so different to men my age.’

Now that was a come-on. But the problem was, I wasn’t single. At the time, I had a girlfriend, Stacey. She was 27, and we’d been together for six months but, frankly, I was already getting bored of her.

Stacey was neurotic about her lifestyle and health, always on a diet and obsessed with protein. She didn’t drink and we rarely went out.

In the cafe, I suggested to Lisa that we meet sometime for a glass of wine.

In a quiet pub a few days later, she told me how she felt lost because her children were growing up and her husband was growing away from her. ‘Does your husband know you’re with me?’ I asked.

She laughed and said he was away again. The kids were out too, so I went back to hers. ‘This will just be a one-time thing,’ she said as she kissed me. But it wasn’t.

For several months, we carried on with our ‘training’, both our usual sessions in the park and our extra ‘sessions’ at her house. ‘I feel like I’m coming back to life,’ she said one Saturday, when we’d taken advantage of an empty house for an entire day.

At the same time, I was also training a 53-year-old woman called Jules. She owned a fashion boutique and I was attracted to her drive and energy. She looked like a French actress, with a cropped bob and a cute fringe.

She too was going through issues with her husband, who was always at home because he’d been made redundant.

He was depressed, she said, and seemed to blame her for everything wrong in his life.

So with Jules, we always went to my flat to have sex. It started when I offered to loan her a massage roller, and we went to mine to get it. She asked if I could show her how to use it, and I could feel her relax into my touch. After that, it felt perfectly natural to start kissing her neck.

Some may be surprised at how easy it was to fall into bed with these women. But when you’re training someone, it’s physically intimate as you’re helping them with stretches and so on.

But I’m not totally unprofessional. All my affairs have been with private clients, not those I’ve met through the gym that employs me, and I’ve never been the first to send a signal. But when a woman tells you she’s in an unhappy marriage, she’s generally asking you to sympathise in a very specific way.

After a few months of sleeping with Lisa, she told me she wanted to stop because she felt guilty. She said our fling had given her the impetus she needed to start having sex with her husband again.

We still train together and it’s not awkward at all. I don’t feel guilty, either.

And in a way, I feel that her husband should have sent me a thank you note. I had taken his wife and made her interested in him again – and she was also fitter and hotter to boot.

I’d have kept seeing Jules for a long time – she was wonderful – but she moved away.

Unfortunately, Stacey found out about her when she saw an old message on my phone.

She was hurt and broke up with me straight away. I’m not proud of that bit.

I’ve since had two other dalliances with clients. There was 42-year-old Laura, who’d become a mother 18 months previously and told me the same sad story: ‘My husband is always away with his work and coming home late. I do all the childcare.’

But we only kissed a few times in the park, as I felt her heart wasn’t in it.

Then three months ago, I had a fling with a 51-year-old woman called Chrissy, who was actually training to become a personal trainer herself. She had a boyfriend, but they were splitting up.

That didn’t last long but like all my flings with older women, it ended in a grown-up way. We’re still friends.

In my view, no one loses in these ‘arrangements’. Before they met me, these women felt sad, unfulfilled, limping along. I gave them back energy and motivation, just like the perfect PT.

Sam Forest is a pseudonym – and all other names and identifying details have been changed