If you find yourself scratching your head over what just happened, you need only resort to this handy list.
1) Did you sweat at all as the events were taking place?
One of the easiest methods to employ is measuring the physical effort you've just exerted. Now, this is what I mean by certain criteria being ambiguous, because even if you stand still in a field, if the weather is 105 degrees Farhenheit, you'll most likely sweat. Subsequently, if you've been sitting in an extremely hot race car, you've also probably been sweating while driving around in that damn circle all day. This doesn't mean you've just played a sport, so don't be fooled by that assumption. 'Sport-related' sweat is always coupled with compromised breathing patterns.
-strictly temperature-induced sweating
2) Was there a risk of danger, or any form of physical harm?
Again, misleading. You could get hit with a stray ball while teeing up on the 1st hole, but that doesn't mean you were at all close to playing a sport before you were put into a coma. What I'm talking about here is harm that you can either inflict or suffer from by means of bodily contact. A sure-fire way to tell if what you've just done was a sport is to consider whether or not phsyical contact was required to compete properly. If it was, then you've just taken part in sport. But even if it wasn't exactly required, it might still have been a sport. Take for instance basketball - you could easily get elbowed in the face while trying for a rebound. I've seen it happen, and it's always hilarious. Thus, basketball is a sport.
-being killed in a car crash
-slipping on ice while sweeping
3) The proximity of other individuals - or even, the presence of other individuals.
Were there other people present? Was the presence of those people even necessary? This is the only criteria that is unequivical. If you can complete a series of actions with absolutely no need for any other individuals (like solo-running your personal-best mile), you've probably only taken part in an activity. Every sport requires people and players other than yourself. There's only one confusing aspect to this - shooting free-throws, skating laps, or spending time in the batting cage are all forms of activity, even though such actions can be combined with other actions to comprise a 'sport.'
-charity races (not a sport)
-golf (don't get me started)
4) Overall fitness of participants.
Did noticably unfit people seem to be entirely unencumbered by their slothfulness? What comes to mind here are both billiards and cards. If you can complete all necessary actions while remaining seated, there's a pretty good chance that you were nowhere close to being an athlete. Also, if you were able to drink more than one beer and not puke or obviously suck more than your sober counterparts, that was definitely not a sport. Sorry, I like to drink too, but only apres-sport.
Well I hope that I've helped to ease everyone's confusion. Nit-picking seems to be something I'm very good at, so I never feel disappointed when forced to step up and clear the air like this. I dare you to try and shoot holes in my assumptions - it won't work, I'm wearing a bullet-proof vest fashioned out of both pride and ignorance.