According to the Univ of Illinois Wellness Center, moderate intensity aerobic exercise consists of walking at 3 mph or slightly faster. This may be called a brisk walk.
Per CDC statistics, it is doubted that 75% or more of US adults walk (a “brisk” walk) for 2.5 hours or more per week. The 2.5 hours would refer to a total amount that week. They could be done in 5 days of half an hour approximately, each day.
Some adults will be so winded after walking 5 or 10 blocks that they will want to stop. Maybe they need to stop.
Some other adults will find that their bod is perceived by them to be overheating or reacting badly in other ways after 30 to 40 minutes of brisk walking.