"It's the fat-burning zone, so I'll lose fat fastest." Per-minute fat burn does peak here, but total fat loss runs on the week's energy balance, not on which fuel a single session picks ⁹. The real prize is teaching the body to burn fat readily all day, not one workout's math.

"Intervals do it all in twenty minutes." Hard bursts raise peak fitness faster per minute, but they build less mitochondria per session and can't carry the weekly volume. Endurance athletes go roughly 80% easy, 20% hard — swap the ratio and the model breaks ¹⁰.

"You need a lab test for your zone." A lactate test is the gold standard, but the talk test plus a chest strap gets you most of the way, and the felt cues sharpen within weeks.

Most people fail by drifting too hard. Heart rate parked above conversational pace but below intervals piles up fatigue with no adaptation — neither payoff ¹⁰. Discipline of the cap is the whole game. The other misses: too little volume (two half-hour sessions is below threshold), doing only easy work with no hard day, and counting ambient steps as the dose. The dog's pace is not the stimulus.

One of the safer things you can start, since the effort is low by definition. Get a clinician's sign-off first for unstable cardiac disease (unstable angina, decompensated heart failure, a heart attack in the last six weeks), resting blood pressure above 180/110, insulin-treated diabetes (dosing needs adjusting to avoid lows), or recent myocarditis. Stable heart failure usually benefits from this and is prescribed in cardiac rehab ¹¹. Uncomplicated pregnancy is not a reason to skip low-impact Zone 2.