Fitness advice: There’s more to getting fit than losing weight – it’s a psychological journey with myriad benefits

We’re all bombarded with fitness articles and adverts at this time of year. Gyms do a huge portion of their annual recruitment during January, when we’re all feeling fragile and fat after the excesses of the holiday season.

But the big gym chains will have already started to notice a drop-off in attendance. Despite all the good intentions, actually going to the gym – and eating more healthily – is tough.

Over the last few weeks I’ve spoken about ways to motivate yourself to keep going, and about ways to make cutting down on calories less painful. This week I wanted to write about something a bit different: the real long-term benefits of getting in shape.

As a personal trainer, it’s great to see amazing sets of before and after pictures. But what’s even more rewarding is hearing the personal stories of what those pictures actually mean to people, how they have changed their lives in a thousand tiny ways.

Some of the most important changes people see aren’t aesthetic but psychological. Losing 10kg may be someone’s target when they first join the gym, but it’s just a number. The real benefits are far more nuanced and personal: being able to take your kids swimming without feeling uncomfortable, walking into a high-end clothes shop and being confident everything will fit, being able to overhaul your wardrobe with clothes that you might not have dared to wear before. People who have taken strides at the gym even tell me their sex lives have improved – they have fewer inhibitions and more energy.

Sticking to a fitness plan can also change your relationship with food in a positive way. People obsess about diets, but one of the joys of being in good shape is the knowledge that you can go out and have a massive meal – bread, cheese, wine, the works – and leave without feelings of shame or anxiety (I’m not suggesting anyone should feel these things, just that many people do).

One of my clients is a food writer and for a small guy he puts away an astonishing amount of food. But he knows that if he puts in an extra shift or two at the gym and skips a couple of breakfasts he can stay in shape and still do his job.

There are logistical benefits for people who are come down from larger weight ranges: one client was able to start horse-riding again, another could fit more comfortably in plane seats. People stop feeling so self-conscious about telling people their weight, not only because the number has decreased, but because they realise that it’s only a number.

You can expect to see improvements in your concentration and sleep, which can have knock-on effects on your performance at work. Few people go to the gym in the hope of winning a promotion, but it’s not beyond the realms of possibility. You’re not just training your body when you go to the gym, you’re reinforcing your personal agency, cementing good habits and improving motivation.

This can be especially helpful for people who are perhaps hitting middle age and realising for the first time that their bodies are slowing down, that they’ve lost the ability to play 90 minutes of football, or run a 10k. A bit of training can knock years off your ‘performance age’. It can also make you look younger, which is a great side effect (the quickest way to do this is to quit smoking, which I’d obviously recommend for any smokers out there).

I’m a big believer in tracking metrics when you’re trying to get fit. But these are a means to an end – the real benefits are subtle, even intangible, and they are the things from which you will eventually get the most pleasure.

• Harry is co-founder of No.1 Fitness, a Personal Trainer-only gym in the City