When I chat to people about their training, the same things come up pretty much every time. The back that tightens up after a day at the desk. The knee that's been a bit dodgy since your 30s. The shoulder that doesn't love anything overhead anymore. And somewhere underneath it, a quiet worry that this is just what getting older feels like.

On their own none of those sound like a big deal. But when you dig a little deeper, it's the run you stopped doing because your knee would swell up for two days after. The surf you keep saying you'll get back to. The game of backyard cricket where you bowl a couple of overs and then find a reason to sit down. Picking up your kid, or your grandkid, and feeling your back twinge, and making a mental note not to do that again.

And it adds up. You start saying "maybe next time", and after a while people stop asking. The kids stop expecting you to join in. The weekend hike gets planned without you because everyone knows your knee won't like it. Nobody says anything, but you notice.

That's the part people tell me about quietly. Frustration with a body that used to just do what you asked. Feeling stuck, because you've tried to get back into it a few times and something keeps flaring up. And for a lot of people, a sense that their best physical years might already be behind them. I hear it from people in their 30s right through to their 60s.

I don't think those years are behind you.

For most of the people I work with, age isn't really the problem. Their body just hasn't been trained to handle the things they want to do. That's fixable, and I've seen enough people prove it over the years to be pretty confident about that.