You signed up for the25percent newsletter.

That tells me something: you’re not looking for “5 easy tips” or “transform in 30 days.” You want protocols that actually work, even if they’re demanding.

Good. You’re in the right place.

But before we start, let me be honest about something.

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This isn’t about biohacking or living to 120

I’m not a fitness influencer. Not a sixpack Bro. I’m not trying to optimize my way to immortality.

I’m a 40-year-old solopreneur running a freelance UX practice while building the25percent app.

Almost 18 months ago, I stumbled onto Peter Attia’s work on what he calls “the Marginal Decade” — those final 10-15 years of life when most people’s physical capacity collapses. His question hit me hard:

Not “how long do you want to live?” but “what do you want to still be able to do?”

Hike with your partner. Travel without mobility anxiety. Pick up your grandkids. Stay independent. Keep doing whatever matters to you.

That reframe changed everything for me.

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I did the research so you don’t have to

I spent months going through the evidence. Peter Attia. Rhonda Patrick. Huberman. The actual studies on VO2max, muscle mass, and mortality risk.

What I found: longevity training is demanding. Four sessions a week minimum. Strength AND cardio. No shortcuts.

But here’s the thing: I also found it’s systematic. And systems can be built.

That’s what I’m building with the25percent: a structured approach to longevity training for people with actual lives and jobs. Not another fitness influencer telling you “just train harder”. Hopefully a system that helps you train consistently.

I’m not inventing anything new here. I’m synthesizing the best research and figuring out how to actually implement it while running a business, managing client work, and dealing with all the same constraints you have.

Roughly every two weeks, I’ll share what I know.

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What to expect from this newsletter

Insights, educational content, actionable protocols.

• No fluff. Just the what, why, and how.
• Evidence-based. I’ll cite my sources.
• Honest about demands. This isn’t easy. I won’t pretend otherwise.

Coming up: Zone 2 and VO2max protocols, strength programming, stress management, mobility. The full picture of what it takes to train for longevity.

But if you want the complete framework now: what longevity training actually involves, how to structure your week, and how to build the habit — I’ve put together a comprehensive guide: The Beginner’s Guide to Longevity Training. Bookmark it, or read it after this.

For now, let’s start with one thing.

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Zone 2 training

Everyone talks about HIIT. High intensity. Maximum effort. The crazy stuff.

But here’s what I’ve learned: Zone 2 — the boring, conversational cardio — builds the engine that powers everything else.

What is Zone 2?

The intensity where you can hold a conversation, but barely. Roughly 60-70% of your max heart rate. For most people: 120-145 bpm.

The talk test: Can’t speak in full sentences? Too hard. Can sing comfortably? Not hard enough.

Why 180 minutes per week?

Large studies show major reductions in cardiovascular mortality with 150-300 minutes of moderate aerobic work weekly (Mandsager et al., 2018). Most longevity clinicians push toward 180+ minutes to maximize mitochondrial density and metabolic flexibility.

I aim for 180. Some weeks I hit 200. Some weeks I hit 120. Consistency beats perfection.

Why longer sessions matter

Here’s what surprised me: three 60-minute sessions beat six 30-minute sessions, even with the same total volume.

Mitochondrial adaptations scale with continuous time in the zone. After 30 minutes, the stimulus becomes more pronounced.

• Minimum session: 45 minutes
• Optimal session: 60-90 minutes
• Weekly structure: 3-4 sessions totaling 180+ minutes

What counts?

Anything that keeps your heart rate in the zone: cycling, running, swimming, rowing. The activity matters less than staying in the zone.

But here’s the catch: 15,000 steps or a relaxed swim won’t cut it. If the stimulus is too low, you’re not getting the adaptation. Zone 2 requires sustained effort at the right intensity, not just moving.

This is why I’d recommend a heart rate chest strap if you’re serious about this. Wrist-based sensors work for trends, but chest straps give you the accuracy to actually train in the zone.

An example split could be: 2x cycling, 1x running or rucking. Running spikes my heart rate fast, so I keep the longer sessions on the bike. Flexibility within structure.

At the moment I’m on a program that requires 3-4 bike sessions a week. So for me, it’s just my wattbike for now.

Start here

If you’re not currently doing dedicated Zone 2:

• Week 1-2: One 45-minute session. Any activity.
• Week 3-4: Add a second session. 90 minutes total.
• Week 5+: Build toward 180 minutes across 3-4 sessions.

Don’t go from zero to 180 immediately. Build the habit first. The protocol only works if you stick with it.

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What’s next

VO2max — the strongest longevity predictor

Attia calls VO2max the single best predictor of how long you’ll live. I’ll explain why, how to estimate yours without a lab, and the protocol to improve it.

Zone 2 builds the foundation. VO2max training pushes the ceiling.

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One ask

Reply and tell me: where are you at with your training right now?

I read every response. It shapes what I build and what I write about.
No reply back, just listening.

Welcome to the25percent.

Alessandro