as an owner of a GSD, And a GSD/Wolf(Jefe GSD, And Buck GSD/Wolf)
I Don't believe they are very active, Buck is very active dog, But hes still in the puppy stage..
Jefe is a very calm dog, Unless he sees the Leash.. Haha..

If you do get a GSD, Just a tip. GSD's Should always be kept on a very short leash, like... maybe a 1 and a half-2 foot leash.