Zone 2 cardio is everywhere right now and everyone seems to be talking about it. It deserves the hype. But there’s a part of the conversation that keeps getting left out, and it’s the part that actually determines whether your fitness improves over time.

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Short answer: Zone 2 is a great place to start. It is not a great place to stay forever.

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So what even is Zone 2?

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Think of it as your “comfortably uncomfortable” pace, the effort where you’re definitely working, but you could still hold a conversation without gasping. A brisk walk, an easy jog, a relaxed bike ride. You’re not cruising, but you’re not dying either. A lot of people refer to it as an easy pace or “conversational pace”.

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Some people may prefer to go off of heart rate, but it’s also not the holy grail either. If you were to base your Zone 2 off of heart rate, it would be 60–70% of your max heart rate. Max heart rate rough estimate/calculation is 220 minus your age.

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The tricky part here is as a beginner, training at different altitudes, getting less sleep the night prior, maybe not fueled or hydrated enough, etc can affect your heart rate and push you OVER that Zone 2 threshold you’ve calculated (or your watch so kindly reminds you of), but you actually FEEL okay, could hold a conversation.

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Basing Zone 2 solely off of heart rate is going to hold you back as well, so use a mix of heart rate but also how you feel. If you didn’t have a heart rate monitor on, would you even care about the exact heart rate if your cardio was feeling great? Usually not.

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Training here builds your aerobic base which is basically the engine underneath everything else. It teaches your body to be more efficient, improves how well your cells produce energy, and is low enough intensity that you can recover from it easily.

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For anyone just getting back into cardio, managing a busy schedule, or dealing with high stress, Zone 2 is genuinely the right starting point.

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The problem with staying in Zone 2

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The problem isn’t Zone 2. The problem is when Zone 2 becomes the only thing you do.

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Your body is really good at adapting. That’s the whole point of training though, you stress it, it adjusts, you get fitter. But once it adapts to a certain level of effort, that same effort stops being a challenge.

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Which means it stops being a stimulus for change and it starts just maintaining.

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If you've been doing the same easy cardio for months and feel like nothing is actually changing, that's probably why.

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Zone 2 also doesn’t do a whole lot extra for your speed or your top-end cardiovascular capacity. To improve those, your body needs to be pushed harder than comfortable. Not all the time, but some of the time.

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What elite endurance athletes actually do

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Here’s something that surprises a lot of people: elite endurance athletes, marathon runners, cyclists, triathletes, spend about 80% of their training time at “easy”, low intensity. And the other 20%, they are going hard in their training.

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What they don’t do is spend most of their time in the middle, that “kind of hard but not really hard” Zone 3 effort that most of us default to when we’re “trying.”

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Turns out that middle zone is where you feel like you’re working hard enough to count but not hard enough to actually drive improvement. It’s the cardio equivalent of spinning your wheels.

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The takeaway: easy should be easy. Hard should be hard.

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Most people have it backwards, they go medium all the time and wonder why nothing’s changing.

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A simple weekly cardio plan

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You don’t need a complicated plan. If you’re doing cardio 3–4 times a week, something like this works well:

• 2–3 sessions at easy Zone 2 effort (conversational pace, 30–45 minutes)
• 1 session where you actually push, things like intervals, a tempo run, hill repeats, or a structured HIIT session

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That harder session doesn’t have to be brutal. It just has to be genuinely challenging, the kind of effort where talking feels hard and you’re relieved when it’s over.

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One important caveat

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If you’re brand new to cardio, postpartum, dealing with poor sleep, or going through a high-stress season, stay in Zone 2.

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Build the base first.

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The intensity will still be there when you’re ready for it.

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The bottom line

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Zone 2 is not overrated by any means, but it is just a bit incomplete on its own.

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Start there.

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Build your base.

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And then, when you’re ready, start adding in sessions that actually challenge you.

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That combination, mostly easy, occasionally hard is where you’ll really start to see these improvements.

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If you’re not sure what “hard” should look like for your body and your goals right now, that’s a totally normal place to be. It’s also exactly what individualized coaching is for.