As some people think, golf is for fat and old people. For leisure players and a regular round, this is true. This a stereotype that has killed golf's respectability with fans of sports such as football, basketball, soccer, etc. However, if you look at Golf being performed at the highest level, pro golfers have to be flexible, strong, and be at peak ability with their swing. For the people who watch the PGA, know it is not even a question. It is only a question for those who don't watch.
Golf is also one of the hardest sports to masters. Just the slightest difference in a turn or ball position is the difference between the difference of a good golf swing and a bad one. Consistency in golf, is one of the hardest tasks to master. No matter how good one may be, it is so hard to dominant every time which is why a Tiger Woods is so rare and most dominance fades so quickly, but a Tom Brady/LeBron James could last for over 15+ years.
All in all, through a narrow view of a sport, golf is not a sport. It is not exciting to the casual eye, the personalities don't boom off the screen. But, by my points I gave above, golf clearly fits the definition of a sport.
If we look at the definition of sport, it gives us the criteria that a game must have physical exertion, skill and competitiveness in order to be a sport. Golf definitely requires physical activity - it requires physical strength to hit the ball far and it has been proven that golfing (without a cart) burns an average of 360 calories an hour!
Also it definitely requires skill as it is probably one of the, if not the most difficult sports to play. No one can pick up a golf club and start hitting balls perfectly and really far. And golf is a really competitive sport. There are huge tournaments all over the world and can be very competitive.