A woman in a long coat on an autumn path between trees

A 21-day plan · Movement

Get fitter by walking

Three weeks of brisk walks that grow a little each week, with a simple test walk to see your progress. No gym, just comfortable shoes.

Test walk
Brisk walk
Rest day: easy stretch
Walk with faster bursts

Download on the App Store GET IT ON Google Play

Run it in the By Day app on iPhone or Android.

For you if

Stairs or hills leave you out of breath.
You'd like to get fitter without a gym.
You sit more than you'd like.

You’ll need

Comfortable shoes.
A watch or phone timer.

How you’ll know

Your test walk on day 21 is faster, or feels easier, than on day 1.
Stairs and hills feel a little easier.
Walking most days feels normal.

What runs when

Days 1–21

Set-upPlan your walking time set-up, day 1
Test walk required, day 1, day 11, day 21
Brisk walk required, days 2 to 6, day 8, day 10, day 13, day 15, day 17, day 19
Rest day: easy stretchoptional optional, day 7, day 14, day 20
Walk with faster bursts required, day 9, day 12, day 16, day 18

Usually 1 required habit a day, never more than three. Day 1 is set-up: plan your walking time. Optional rows never count toward your results or a lifetime place.

Checkpoints

Day1
Set-up: plan your walking time. Set a reminder for it.
Day3
Your legs may feel it. Keep the pace brisk, but easy enough to talk.
Day8
Week-one check-in: a short look back, then keep going or stop. Stopping never counts against you.
Day11
Second test walk. Compare it with day 1: your time, and how hard it felt.
Day21
Final test walk. Compare all three, then decide how often you'll keep walking.

Why it works

Your heart and lungs get fitter when you regularly ask a bit more of them than usual. For people who are starting out, brisk walking does exactly that, and short bursts of faster walking add a little extra challenge without running. Doing it most days matters more than going hard.

Regular walking improves aerobic fitness in adults who were inactive, and alternating faster and easier minutes of walking can improve fitness more than steady walking. Health guidelines recommend 150 to 300 minutes of moderate activity a week; this program works up to about that. Bigger changes, like a lower resting heart rate, usually take months, not weeks.Sources

Results

If you connect Apple Health, Health Connect or Oura, the plan adds daily steps and exercise minutes and resting heart rate, measured against your first nights and marked still forming until day 14. What you notice yourself is the main measure.

Before you start

Check with a doctor before starting if you have a heart condition, have had chest pain, dizziness or fainting during activity, or have been told to limit exercise.
Stop and get help if you feel chest pain or pressure, unusual breathlessness, or dizziness.
If a joint stays sore for more than a day, shorten the walks or pick a flatter route.
Walking in the dark or near roads: wear something easy to see.

Access

Now: Free, with every feature, during the open beta. No card, no end date yet.
A lifetime place: Finish your first full 21-day plan during the beta with at least 80% of its required habits done and, if fewer than 200 people have qualified before you, Explorer is yours for life straight away. Stopping early doesn’t count against you; the first plan you run to its end is the one that counts.
After the beta: One active plan, daily habits, mood, recaps and history stay free. Explorer, the paid tier, adds every plan and connected health readings.
Where: The By Day app on iPhone and Android, to run it and to look back.