On the mornings I'm not playing rounds I use an Aqua Track at a local Recreation Center. A 3 1/2-foot-deep pool with a meandering circle, and water jets pushing back against you. 27 laps is one mile, I spend an hour in it. Builds strong legs, and I paddle to keep my arms firm. 3-4 times a week, and I burn about an average of 800 calories.
I think it helps with my leg work on form, and arm whip as well. Also, helps on the course not getting fatigue I always play at least two rounds in the morning and sometimes a third, including ravine courses. The only course that kicks my behind is The Lake Marshall Lions' course, long with up and down steep hills.
In the photo the aqua track is on the left, you should be able to see the divider.