Right now I have 2 aussies and 2 GSD's..The aussies being 7 & 6 yrs old, the GSD's being 12 & 10 yrs old. I've had them all since puppies.
My female gsd is /was an energizer bunny, she is a dog who as a puppy, NEVER ever took a "nap" like most puppies do *vbg*..She honestly did not start slowing down until she hit about 10. She still, crippled with arthritis, never 'walks', she 'flits'....My male gsd is more laid back, however, he'll work all day if you ask him but lounge on the couch all day if that is required..
My aussies on the other hand,,my male out of working lines, is much like my male gsd,,he is much more intense & serious, and will chase a tennis ball all day long or until he dropped dead I'm sure...but he isn't 'demanding' or has to have constant exercise. My female however, never stops, she is very demanding and has to have hard workouts atleast 2-3 times daily. Walks have never cut it for any of my dogs, they need to run, chase balls, catch frisbees, hike, something that engages them. Training also is an outlet for them, classes in agility/obed , fun herding .
If we have say, a really rainy day, my female aussie is a bear to live with. Lucky for her (not really for me!) she doesn't mind getting wet and is willing to take on bad weather to get in her daily exercise.
There are loads of the higher energy dogs that can be found that are not high energy or as demanding, I happen to like demanding little demons .
Diane