Healthspan is mostly behavioral. Don't smoke, move enough, sleep enough, build muscle, manage cardiometabolic risk. Every Tier 3 longevity intervention combined is smaller than getting Tier 1 right. Lifespan is how long you live. Healthspan is how many of those years are functional and well, free of cognitive decline, mobility loss, and chronic-disease management as a full-time job. The gap between the two is closing for most people in the developed world only at the lifespan end. The functional years are not gaining at the same rate.
The Tier 1 levers, ranked by effect size in the literature: cardiorespiratory fitness, non-smoking, sleep duration and timing, resistance training, cardiometabolic risk management (ApoB, blood pressure, glucose). Each has dozens of large prospective cohorts and multiple RCTs supporting it. Mandsager 2018 (n=122,007) showed people in the bottom 25% of cardio fitness die earlier than people with metastatic cancer. The smoking signal is even larger and well-known. Sleep restriction below 6 hours per night roughly doubles cardiovascular and metabolic disease risk over decade-scale follow-up.
The Tier 3 conversation is where most beginners get lost. Rapamycin, NAD precursors, senolytics, GLP-1 for non-obese aging: each has a plausible mechanistic story and weak-to-moderate human outcome data. Combined, they are smaller than getting cardio out of the bottom quartile. People paying $300/month for NAD IVs while not lifting have a priority problem, not a budget problem.
Cardiometabolic management is the one Tier 1 lever where pharmacology routinely matters. ApoB above ~80 mg/dL adds cumulative atherosclerotic risk year over year. Most adults over 40 cannot hit a sub-80 ApoB on lifestyle alone and will benefit from a statin or ezetimibe. Same logic on blood pressure and HbA1c if drift is sustained. This is not Tier 3. This is treating the dashboard.
The mistake to avoid early: treating longevity as a stack-building project before treating it as a behavior-architecture project. The supplements don't matter if you sleep 5 hours a night and don't lift. They matter at the margin once the architecture is built.
- Cardio: Get out of the bottom quartile of cardiorespiratory fitness for your age and sex. The single highest-leverage longevity intervention.
- Don't smoke. If you do, quitting at any age improves expected healthspan more than any other available intervention.
- Sleep: 7 to 9 hours, consistent timing. Sub-6 hours roughly doubles cardiometabolic disease risk over decades.
- Resistance training: 2 to 3 sessions/week. Defends against sarcopenia, frailty, and falls, the late-life lethal trio.
- Cardiometabolic dashboard: ApoB <80 mg/dL, blood pressure <130/80, HbA1c <5.6%. Test annually.
What to actually do
- Take a baseline. A standard lipid panel plus HbA1c plus blood pressure plus a rough cardio fitness estimate (Cooper 12-minute or Rockport mile). 60 minutes total, costs <$100. This is your dashboard.
- Walk every day, lift twice a week, sleep at consistent times. That is the floor. Adding before this is built is rearranging deck chairs.
- Revisit the dashboard in 6 months. If anything is off-target after 6 months of consistent Tier 1, that is when pharmacology (statin, blood pressure medication) enters the conversation. Not before.
Healthspan is an unsexy long game. The compounding interest is enormous. Tier 1 is uncopyable, unsellable, and free, which is exactly why it works and why it gets undersold. For the full ranked breakdown of every intervention by evidence tier, see the full article.