Python wrote:
Have you ever heard of a speed workout? or are you using the term 'workout' to mean any type of physical activity? I usually only hear that from inactive people.
You need around 15 minutes for aerobic benefit. I don't count anything under 20 min except warm ups and cool downs.
Workout to me means speed workout too (that is to say, a broad category encompassing anything uncomfortable, from balls out 200s to a 10k tempo on the roads).
I usually don't do less than three miles, but I count any running I do as running (i.e. I count warmups and cooldowns but not running to catch the bus or playing pickup soccer).