Although it's one of the most common procedures performed on dogs, spay surgery is a big deal -- the equivalent of a hysterectomy in a woman. Most women who've gone through such major abdominal surgery aren't ready to run around like crazy a day or so after the operation, but that's not necessarily true of energetic female dogs. It's up to you to ensure your newly spayed dog doesn't overdo and recuperates safely.
After bringing your dog home from the vet, restrict her activities for the next week to 10 days. Your dog shouldn't indulge in any real exercise for at least two weeks post-surgery. That means talking her out on short walks so she can relieve herself, not letting her loose in a fenced yard where she could run and rupture her incision. She might have to wear an Elizabethan collar -- also known as the "cone of shame" -- to prevent her from licking or biting at the stitches.