How to use the online timer
Thirty minutes at a brisk pace counts as moderate activity, and brisk has a useful definition: quick enough that talking is easy but singing is not. That is noticeably faster than an amble and slower than a march. UK activity guidance is built around accumulating roughly this much moderate movement on most days, and a walk is the least demanding way to reach it, requiring no kit and no changing room.
Route changes the effort more than pace does. Thirty minutes on the flat around the block is a different thing from thirty minutes over hills or across a muddy field in November, even at a similar heart rate. If you want the effort to be consistent day to day, keep the route consistent too, or accept that the hilly version is doing more work in the same time.
Posture holds up better than most people expect, provided the phone stays in a pocket. An upright stance with the arms swinging naturally keeps the neck and shoulders out of it, whereas half an hour spent looking down at a screen leaves them stiff by the end. A walk after a meal is a particularly easy half hour to find, and the commute counts too if part of it can be done on foot.
Common questions
What counts as brisk?
A pace where talking is easy but singing is not. That is noticeably faster than an amble and slower than a march, and it is the level UK activity guidance is built around.
Does a hilly route change anything?
Yes, considerably. Thirty minutes over hills or soft ground does more work than the same time on the flat, so keep the route consistent if you want the effort to be comparable day to day.