HRV + resting heart rate

The only daily, at-home, free biomarker pair (watch, ring). Every +10 beats of resting HR tracks with 10–20% excess mortality; a drop in HRV is a sensitive signal of poor sleep, alcohol, illness and overtraining — days before symptoms. The trend matters, not one day's number.

Continuously, from overnight readings; look at weekly averages.

Zone 2 cardio (the most effective HR reducer), no alcohol (one drink –5–10% HRV), regular sleep timing, breathing practice (6/min), no evening coffee.