Is Walking Enough Exercise?
Brisk walking can count as moderate activity; the useful question is how it fits your complete week.
Walking can provide meaningful aerobic activity, especially when the pace raises breathing and heart rate. Complete health guidance also includes strength work and, for many older adults, balance activity.
Intensity belongs to the person
The same pace can be easy for one person and demanding for another. A practical moderate-effort check is that you can talk but not sing comfortably.
Ordinary minutes can accumulate
Activity does not have to happen in one formal workout. Walks for transport, breaks, errands, and deliberate exercise can all contribute.
Enough for what?
Walking may be enough for your current health goal and not enough for a future race goal. Let the answer change as your capacity and ambitions change.
Reference point: Current public-health guidance says some activity is better than none, adults can combine moderate activity such as brisk walking with vigorous activity such as running, and inactive people should start small and build gradually. See CDC adult activity guidance and the NHS Couch to 5K introduction.