Physical activity? What about Darts? Bowling? Curling? How about ping-pong?
What, then, of VR games, or games like those on the Wii that have a little remote and require you to stand and swing your arm?
How much physical activity crosses the threshold to be deemed worthy of the vaunted title of 'sport'?
Shooting events are considered sports but most of the time the user isn't moving.
Archery, again, is a stationary 'sport'.
How about Nascar? Literally professional car sitting - but say that in the wrong place and you're liable to start a fight lol.
How do you measure physical activity that counts towards being a sport? Heart-rate, calories burned, sweat production, number of muscle groups engaged? I would imagine that most "esports" hit all or most of those boxes (however you define them), probably better than things people would prefer to call "sports".
IMO, way to many things are considered 'sports'. I feel that physical activity is the least important factor. Honestly, anything that doesn't involve some kind of team playing activity, like cross-country, swimming, gymnastics, cycling, etc. shouldn't be considered sports.
But since people get all grumpy when you call whatever their thing is "not a sport", I fall back to a more broad definition. A sporting event is a money making enterprise where people practice a skill and compete against others, it because 'professional' when the competitors get paid. So for me, pretty much everything from football to Starcraft is equally a sport.

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All that aside, I just don't understand the attachment people have to the word. I could never wrap my head around why people get so excited about this conversation (I don't mean anyone here specifically, more so the people in my life who I have seen get into very heated arguments on this topic). Call it a sport, don't call it a sport, who really cares - why does it create such an emotional response (generally speaking)?