If anyone knows how to live the good life, it’s Felicity Kendal. Way back in 2009, she told The Guardian that she exercised ‘not so much for how it makes me look, but for how it makes me feel’. Her routine, she said, included yoga, weights, swimming and ‘fast walking and slow jogging’.
Nearly two decades on, as she approaches 80, her long-term, low-key approach to fitness looks particularly relevant. Kendal’s combination of brisk walking and gentle jogging reflects what exercise scientists describe as zone 2 cardio – a steady, moderately intense level of aerobic training that has become increasingly popular.
What is zone 2 exercise?
‘Cardiovascular training can be divided into different zones, usually from 1 to 5, depending on how hard you’re working,’ explains Good Housekeeping fitness expert Kim Hawley. Cardio has a whole host of benefits, she explains, including:
Improving heart and lung fitness, so you can do more with less effortLowering resting heart rate and blood pressureImproving circulation and the body’s ability to use oxygenReducing the risk of heart disease, stroke and type 2 diabetesHelping regulate blood sugar and support healthy cholesterol levelsImproving stamina, energy and recoverySupporting sleep, mood and stress managementHelping maintain a healthy body weight
A 2025 expert review described zone 2 as exercise performed below the first lactate threshold. For the uninitiated, lactate is the biological byproduct created when your cells break down glucose (sugar) for energy and the threshold is the point at which the body begins accumulating it faster than it can clear it.
Essentially, says Kim, ‘It’s a steady-state, low-to-moderate intensity exercise.’ For some people, that might mean walking quickly. For others, it could mean a slow jog, an easy cycle or swimming at a steady pace. The right intensity depends on your fitness, age and health, which is why fixed heart-rate formulas are not always reliable.
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How can you tell if you’re in zone 2?
‘It should be hard enough to raise your heart rate and breathing, but easy enough to sustain for a fairly long time,’ says Kim.
Use the talk test:
You’re breathing faster and feeling warmer, but you’re not struggling.You can hold a conversation, but you probably could not sing comfortably.You could maintain the effort for roughly 30–60 minutes, depending on your fitness.What are the benefits of zone 2 exercise?
Alongside muscle-strengthening activity on two days of each week, the NHS recommends that adults aim for at least 150 minutes of moderate activity. That can include brisk walking, cycling, swimming and active hobbies, and it can be spread across the week. Why?
‘Exercise scientists agree that cardiovascular training can improve your muscles’ mitochondria – tiny structures that help turn oxygen and fuel into energy,’ explains Kim. ‘They’re often described as the “powerhouses of the cell”, although this is rather more catchy than scientifically comprehensive.’
A 2025 systematic review and meta-regression of 353 studies, involving almost 6,000 participants, found that low-, moderate- and high-intensity training could all stimulate improvements in skeletal-muscle mitochondria. In other words, you can work your heart and lungs without needing to sprint, lift heavy weights or recover for days afterwards – especially good news for those dipping their toe into exercise for the first time or after a break.
The catch
‘Zone 2 is popular because it offers a sensible balance between effort and recovery; it gives the benefits of cardio training without feeling completely flattened afterwards,’ says Kim. ‘It’s not the Holy Grail – harder sessions will also improve fitness, often in less time, but, as always, the best routine is one you can do consistently, whether that means walking, cycling, swimming, running or having a kitchen disco.’
Maybe that’s the most valuable lesson in Kendal’s approach: the best routine is often the one you can keep doing for decades.
How to get into zone 2 from scratch
Start with 20 to 30 minutes of brisk walking on several days each week. When that starts to feel comfortable, add short intervals of slow jogging, perhaps one minute of jogging followed by two or three minutes of walking. Build up gradually and allow your pace to be guided by how you feel, rather than by someone else’s target.