A break from exercise costs less than you might expect. What four studies say about the strength you keep while you’re away, how fast it comes back, and a gentle plan for your first fortnight.

Winter is a good time to get fitter: the class comes to you at Jim’s Gym and nobody has to scrape a windscreen first. What the research says about keeping the habit going when the days are short, dark and cold.

If your body gets you up the stairs, round the shops and through a decent walk, it's worth more than whatever the scales said this morning. What the research actually says about muscle, metabolism and the number that matters less than you think.

If you can stand up and sit down, you already own a strength machine. It goes everywhere with you, it never needs plugging in, and nobody else is hogging it. Five exercises, no kit, and the research behind why slow beats heavy to start.

Cardio gets talked about as one thing. It's three: your heart, your lungs and your circulation, working as a team. What training does to each one, told straight, and the everyday wins you'll actually notice.

There's a state I think of as the zombie: never properly asleep, never properly awake. The way out isn't waiting for sleep to turn up on its own. It's earning it, and the research shows exactly how.

An engine that only ever idles down to the shops doesn't get an easy life, it gets a shorter one. Bodies work the same way. Why pottering isn't the safe option after 50, and what hard enough actually feels like.

You can tell a lot about someone from how they get out of a chair. You can't tell whether they slept well, laughed this week, or have anyone to ring on a Tuesday. That's the bit the mirror misses.