Cold days and dark nights don’t make that easy, of course. But maintaining motivation is done far more easily when others are involved, which is why sports work so well. Tennis is an incredibly social game, with a 22 per cent rise in recreational players as a result of the pandemic, and football too; for men especially, a little competition can go a long way to keep interest up. Wild swimming – another lockdown favourite – has provided a boost for many groups of women, too. Fun activities that make you feel good, and can be shared with others, are easiest to stick to in the long term.

If you don’t have that option, begin your body reset solo, starting with a long, fast-paced walk – 45 minutes or an hour – at least five days a week. You want to get used to doing sustained activity at a medium level, as the healthier you are, the more efficiently you can burn fat. Then, start giving your body a challenge: beginning with at least one day a week in which you overload or kick up your heart rate. That can be interval training, of 20-30 minutes of high-intensity exercise; it should feel like you’re at 90 per cent of your maximum ability. 

It could be in the form of running up and down a staircase for 30 seconds, resting until you feel in control again, then repeating the same: start with five to six repetitions. That might take just 10 minutes in total – yet even that will give your metabolism a major shove up the backside. It will increase the capacity of your lungs, and the strength of your heart tissue, so ensure you are bringing in both medium and higher intensity activity for those first few weeks. 

Once you’ve got into a good routine, the next focus is strengthening your core – the area from your ribcage to just beneath the hips. Your glutes and abdominal areas are key to stability: get them in good shape, and your body will be able to handle any intensity and duration you throw at it. Glute bridges are a brilliant way to activate your largest muscle group. Begin by putting your feet on a bench or step, while lying on your back, and raise your bottom up and down, clenching at the top of each bridge. Do 20 or 30, four or five times, with a rest of a minute or so in between.

For the abdominals, a basic plank – elbows and toes on the ground, supporting the body – or mountain climbers (palms down, while bringing your knees to alternate elbows), should be incorporated into your routine twice a week. Five days of long, moderate intensity, one or two days of high intensity interval training and one or two days of core development work across that first month should get your body more stable, fitter, and more efficient at burning fat.

It’s important to make activity a daily thing, however unfit you are when you start.

For those who are older, 20 minutes of walking, upping the duration over time, is a good entry point, even if it involves stopping and starting: being on your feet and getting the blood moving will improve circulation, and trigger an anti-inflammatory response, boosting immunity and lowering risk of infection. Being off your butt, and on your feet, is the primary goal here. Can you incorporate a walk into your commute? Could you stroll further?

It’s also an easy way to build more activity into your life, which can be important after injury. Physical setbacks are just those; see a strain or break as a period to restore yourself, before beginning a regimen again. You lose two to five per cent of your fitness for each week you’re off your feet, so even a month needn’t push you back too far. And, once you’re ready to return, go in slowly, reducing the intensity of your workouts by around 10-15 per cent, and upping the burn as time goes on. Avoiding injury is best done by keeping joints and muscles strong, and bone density high: resistance training, such as lifting heavy weights, stimulates the nervous system and boosts hormone production. This will regenerate the likes of tissue cells, ligaments and skin, too.

But there’s more we can do. I’ve trained tens of thousands of people in my three decades in the fitness industry, and increasingly, it’s not just weight loss but living longer that they cite as their primary goal. One of the simplest ways to achieve this is with an eating window of 16:8 – that’s two meals in eight hours, and nothing for the 16 that follow. Those two meals should be around 40 per cent protein, 40 per cent good fats (avocados, oily fish, nuts) and 20 per cent carbohydrates. Cruciferous foods like dark leafy greens are full of antioxidants, and a highly varied diet is crucial for a balanced microbiome, which determines our gut health. 

Start jotting down how many plant types – that includes lentils, pulses, grains, you name it – you eat in a week. If you’re above the 50 mark, you’re doing well; below 30, it’s time to broaden your appetite. Biodiversity reduces the likelihood of developing irritable bowel syndrome, increases your immune response and allows you to metabolise food more effectively.

Something else you need to be on top of is your sleep – too little can disrupt your body’s ability to metabolise food, as well as raising glucose intolerance and insulin resistance, so it’s central to maintaining your weight.

Many people have come to me reporting that Covid has eroded their work-life balance and heightened their reliance on comfort food and repeated late-night snacking. Our movement patterns have been limited by having sat for so long in bed or at the kitchen table; our hip flexors have shortened, our glutes have weakened, and our abdominal strength has diminished. Throw weight gain into the mix and that’s adding extra load on to weakened structures. 

Any pain is an inhibitor to exercise – if you’re not feeling great, you’re not going to do it – so stay on the move; the more mobile you feel, the more engaged you’ll feel with the idea of exercising. Yoga and Pilates are good options to try at home, but think about your posture in the small moments of the day, too, and to incorporate mobility work into them. While waiting for that spaghetti to boil, say, do a quick spread through your quads, calf muscles and back. 

We don’t know how long we might be living under far-from ordinary circumstances, so focusing on and boosting our health is vital. Get a grip, make a goal to reset and stay focused; in no time at all, those benefits will make themselves clear.

As told to Charlotte Lytton

Matt Roberts’s new podcast, Evolution Lab, launches in January. 

Join Matt Roberts and other leading experts in the new year for The January Health Reset, a series of online events focused on health, fitness and wellbeing throughout the month of January. To book tickets visit telegraph.co.uk/events

Don’t miss part two of the 2022 Health Reset tomorrow, when we’ll be looking at how to reset your sleep