150 – 300 min/wk	Moderate intensity (brisk walking, cycling)
75 – 150 min/wk	Vigorous intensity (running, HIIT)
2+ days/wk	Strength / resistance training
Reduce	Prolonged sedentary time — break every 30–60 min

Additional benefits come from exceeding 300 min/wk. Any movement is better than none.

Max HR estimate: 220 − age

Zone 1: 50–60%	Recovery — light walking, warm-up
Zone 2: 60–70%	Fat burn — easy jogging, long rides
Zone 3: 70–80%	Cardio — tempo runs, sustained effort
Zone 4: 80–90%	Threshold — intervals, race pace
Zone 5: 90–100%	Max effort — sprints, short bursts

Most training (80%) should be in Zones 1–2. Only 20% in Zones 4–5.

Light activity	24h recovery — walking, yoga, stretching
Moderate	24–48h — steady-state cardio, moderate lifting
High intensity	48–72h — HIIT, heavy lifting, long runs

RHR check: If resting heart rate is 5+ bpm above your baseline, your body hasn’t recovered — take an easy day.

Minimum: 1 full rest day per week. Active recovery (light walking, mobility) counts.

The 80/20 Rule:
80% of training at low intensity (Zones 1–2), 20% at high intensity (Zones 4–5). This applies to elite athletes and beginners alike.

Weekly structure:
• 2–3 strength sessions
• 2–3 cardio sessions
• 1–2 flexibility / mobility
• 1 rest day minimum

10% rule: Don’t increase weekly training volume (time or distance) by more than 10% to avoid overuse injuries.

Calorie burn depends on body weight, intensity, and workout type. Wrist-based estimates have ±15–30% error margin.

Rough benchmarks (70 kg person):

Walking (5 km/h)	~250 kcal/h
Jogging (8 km/h)	~500 kcal/h
Strength training	~350 kcal/h
Yoga	~200 kcal/h
HIIT	~600 kcal/h

Stop and rest if you experience:
• RHR consistently 10+ bpm above baseline
• Persistent fatigue despite adequate sleep
• Declining performance over 2+ weeks
• Joint pain that worsens during exercise
• Dizziness or chest discomfort during workouts

Overtraining syndrome can take weeks to recover from. Prevention (rest days, deload weeks) is far easier than treatment.