It seems to me that golf is so great because it gives you the variety of all sorts of opponents, or none at all.
You can play golf with your own mind as the primary opponent.
You can play golf with the course as your opponent.
You can play golf with one or multiple opponents, including a whole field in your tournament.
You can play with nothing but a walk and a series of hit and find and hit again, no opponent.
Or you can play with any combination of the above.
I most often play with a couple of these opponents at a time. I always have my own self to overcome in terms of game-course management, ego or timidity on various shot challenges. I usually have a match or fellow playing competitor opponents, even if it is a quarter skins game, $2 nassau or whatever.
The course is often one of my co-playing competitors. Particularly, if it is a course I am intimately familiar with.
I know if I beat the course when even if all the other playing competitors have beaten me, I can still say I shot my handicap or a number that is appropriate for that day's conditions, and I did it with some skill, knowledge of how the course plays and execute a percentage of the time that yields a score in relation to my handi.
It doesn't always have to be about that score relative to the handi or the number approriate for that day's conditions, but I do have that concept in mind more often than not as a desire to beat the course. I can play mindlessly with no opponent at times. Or some say I do that all the time....