Exercise is indisputably one of the best things you can do for your brain and body. Which begs the question (at least from me) ― what’s the absolute bare minimum I have to do to get by?

So, we at HuffPost UK thought we’d speak to some experts about the topic for the sake of ourselves any curious reader.

We chatted to Dr. Richie Kirwan, Lecturer in Exercise Physiology at Liverpool John Moores University (LJMU), and Olivia Tyler, National Fitness Assurance Lead at Nuffield Health about what exercise is, how much of it we need to do, and whether or not the levels change as we age.

Here’s what we found out:

“The UK currently has guidelines for physical activity which is different from exercise,” Dr. Kirwan informed HuffPost UK.

“Physical activity is any movement that requires you to use energy to move your muscles so can be things like walking or cycling to work, cleaning the house, gardening, etc.

“Exercise, on the other hand, is any structured/planned movement that we carry out with the specific goal of improving or maintaining our health or fitness ― so cycling to work is physical activity but going for a cycle after work to stay fit is exercise.”

You’ve probably heard recommendations for 150 minutes of physical activity a week.

But, Dr. Kirwan points out, this is for moderate-intensity activity; it drops down to 75 minutes if you’re going harder (ie exercising to a level that makes breathing hard and fast and makes it difficult to speak).

“We [at LJMU] have a lot of research showing that vigorous or more intense activity is more probably more beneficial, or equally beneficial in a shorter period of time,” the doctor points out, “but combining moderate and vigorous is probably an even better option.”

Well, don’t skip taking the stairs and enjoy your morning walk if you can, as moderate physical activity is great. But possibly, yes ― adding some intensive exercise may be a less time-consuming way of getting those minutes in.

“At LJMU we’ve done quite a bit of research on High Intensity Interval Training (HIIT) and shown you can get many of the cardiovascular benefits as more moderate exercise in a shorter amount of time,” Dr. Kirwan shared with HuffPost UK.

“And in the modern world, many people are time-poor, so time efficiency is important.”

Then, there’s lifting weights and doing other strengthening exercises; these can help to prevent “muscle and strength loss with ageing (called sarcopenia)”, Dr. Kirwan says. Sarcopenia is associated with conditions like diabetes, heart disease, and bone conditions.

“Doing strength-focused weightlifting workouts can take more time as you need more rest between your sets to recover so this might not be achievable when life gets really busy,” Tyler said.

But “Some people like to split their weeks into different areas of their body, for example doing chest and tris on one day, back and bis on a separate day and legs on another” ― this can help to save time.

Grip strength is a greater indicator of cardiovascular risk among older people than even blood pressure ― so it’s no surprise that Dr. Kirwan says “exercise is something we should all do throughout our lives but is probably even more important for older people.”

He added that while older people newer to exercise “should speak with an exercise professional who can introduce them to the correct activity and intensity to start at (based on their fitness level and mobility),” age shouldn’t deter people from intense activity.

He mentioned one study involving a 93-year-old Irish rower who took up the sport at 73 and became a champion in his 90s.

70% of his routine consisted of the easier physical activity we talked about earlier ― but when he did practice rowing, he upped the intensity week on week.

“A lot of people don’t think about progression at all but it’s important,” Dr. Kirwan said. “We get used to exercise eventually and need to continue to challenge ourselves with intensity etc.”

Both experts agree that some exercise is always better than none, across all age groups.

“The guidelines are that anything is always better than nothing. Your workouts should be built into your week as part of your routine and so you can only fit in what you have time for,” Tyler says.

Dr. Kirwan agrees, saying “if someone is completely inactive, starting any form of physical activity (as long as it’s not too strenuous) is beneficial.“

But to make those minutes count more and work harder, it’s a good idea to combine sneaky workouts (like gardening, cleaning, and walking to the shops) with intentional exercise sessions; if you want to chop down your time in the gym, make those intense, and try to progress in your chosen exercise every week.

Strength training is important, too ― by mixing up your workouts and strategically moving your body, you should be able to optimise the 75 minutes of moderate-intensity exercise (or 150 minutes of more easy-going physical activity) experts prescribe.