That depends on your pace and your previous level of activity. If the pace is average and your previous level was ~0 then yes, you're expected to benefit a lot for not much effort.

But to answer your question, walking at average pace is not extensive exercise by any means. Walking at top possible speed would be closer but would probably still not meet the bar. You'd need to incorporate running at moderate pace with a few periods of all-out sprinting into your walking routine.