The physical stress that race car drivers undergo during a race is quite phenomenal.
[This goes OT if you want to skip it.]
No argument, you are right. But the stress of hitting 18 drives where you want them under pressure, the stress of positioning the ball exactly where you want it on a green from 200 yards out under pressure and the stress of making a twisting, downhill nine-foot putt when a championship and hundreds of thousands of dollars are on the line produce serious physical stress as well.
But, to the point that has been raised. I long ago decided to think of Golf as "A Game that can be played like a Sport."
Let's face it, even on the PGA Tour up until the advent of Tiger there were a lot of guys out there who were clearly out of shape and at times smoking cigarettes as they made their way around the course (who knows what they were drinking from their "water bottles"). It's a tribute to their enormous talent that guys like Craig Stadler and John Daly could play the game at a high level, given their noticeable lack of conditioning. Arnie was in pretty good shape, but smoked his way around the course. The early Jack Nicklaus was pudgy, but he lost weight and improved his conditioning as he got older.
With the advent of a new generation of players, led by Tiger and Veej, a premium is now placed on aerobic and anaerobic capacity as well as flexibility if you are going to play at the highest level. Absent the otherworldly talent of a Daly, without a high level of conditioning it's almost impossible to consistently hit 320+ yard drives to the right location and then have the strength to consistently make the kind of precision approach shots from long distances that today's Championship Courses demand. I often wonder how great Stadler and Daly might have been had they played the game in great shape, putting aside for the moment Daly's well-documented off-course problems. Even Phil Mickelson, long known for his love handles, got the conditioning bug and now plays in great shape.
But, the reason that golf is such a great Game/Sport is that the average idiot like myself who is in OK shape for his age can not only score decently on more forgiving courses, but can actually improve as s/he gets older, until of course the markers of time start to become undeniable.
Clearly the "Game" of Golf can be played by out of shape, beer drinking guys out for a good time with their buddies. And, that's just great. The "Sport" of Golf can be played by guys who try to keep in shape, have an exercise regimen designed to improve their game and who "practice, practice, practice."
And, Game or Sport, we can play the same courses as Phil and Tiger (though not necessarily from the same Tees nor when groomed for a Tour event or Championship) and at times can have the rare, memorable moment of making a better shot than we saw them execute on TV from the same place in the Fairway (of course, we'll likely never do it again and we're also doing it without a few million people watching us on TV, without a thousand fans within a few dozen yards of where we are standing and without the pressure of trying to win a tournament). Still, we never forget those moments. It's what keeps us coming back.