Personalised longevity

Every chapter so far has given you general principles. This one is about turning them into a plan for one specific person: you. Personalised longevity isn't about expensive tests or genetic reports. It's about knowing your numbers, knowing your bottleneck, and running your own experiment, one change at a time.

You are an experiment of one

Average results from studies tell you what tends to work. They can't tell you exactly how your body will respond. Two people can follow the same diet and see very different changes in their weight, blood sugar or cholesterol. The only way to know what works for you is to try it and measure.

What makes your plan yours

Your level and your bottleneck. The biggest personalisation is also the simplest: which level you're at, and which box is red. That decides what you work on for the next 90 days.

Your family history. Heart disease, diabetes, certain cancers or dementia in close relatives, especially before 60–65, changes what you test and how early. Tell your doctor.

Your genetics, with care. Some genetic results matter a lot: familial hypercholesterolaemia, BRCA variants, or APOE4 for Alzheimer's risk. If you choose to test, do it with a clinician or genetic counsellor who can explain what the results mean. Most consumer "polygenic" scores for diet or fitness add little to what your blood tests and family history already tell you.

Your life. A plan you can't follow is worse than a modest one you can. Shift work, young children, travel, injuries and budget are all part of the design brief.

How to run your own experiment

1. Pick one change, aimed at your bottleneck.
2. Define the number that should move, and by how much.
3. Do it for 30 days, consistently.
4. Retest under the same conditions.
5. Keep, adjust or drop it. Then pick the next change.

One change at a time is slower, but it's the only way you'll know what actually worked.

Your plan on one page

Write it down:

• My level and my bottleneck
• My identity line: "I am someone who…"
• My training week, in one line
• My three food rules
• My bed time and phone-down time
• My supplements, if any, and why
• My accountability partner, and when I send them my score
• My why, in one line

If a plan doesn't fit on one page, it's too complicated to follow.

Working with professionals

A good GP, and where needed a cardiologist, dietitian, physiotherapist or psychologist, is part of a personalised plan, not a replacement for one. Bring your numbers and your trend. You'll get far better care as an informed patient who knows what they're trying to change.

Where to go from here

If you haven't yet, go back to the Testing & tracking chapter and find your level. Take the Longevity Score. Then pick your bottleneck and start. Ninety days from now, retest and see what changed.

And look back at the note you made in the Biological age chapter: the age you feel. Write it again in 90 days.

Key idea
Lowest level with a red box. One change at a time. Measure, adjust, repeat.

This week

• Write your plan on one page.
• Pick your first 30-day experiment.
• Tell one person what you're doing, and ask them to check in with you.

In the journal

The journal is this chapter, bound: your plan on one page, your bottleneck on every evening page, and a daily score that tells you whether it's working. See the journal.