Walking on two legs and using her front legs--she had to remember that the humans called them "arms"--to grasp things with her long, flexible fingers, so different from hooves, wasn't as much of a challenge as Jenny had feared. It was as if the human body she now wore came with certain instincts that helped her handle herself.
The real challenge was dealing with her new sense perceptions. She had heard humans talk about "colors" before, but never really got the concept. Now it was like bright colors, like the "green" of grass, were stabbing her eyes, but in a way that was somehow wonderful. She had to close her eyes periodically just to rest her brain from these new inputs.
But just as she had gained in vision, she had lost in smell. She kept sniffing the air as if taking in big breaths through her nose would somehow restore her equine sense of smell, but it was gone. She could barely make out the smells she did receive, in contrast to her life as a horse. No wonder the humans didn't greet each other by smelling!
And she felt so little in comparison to being a horse! Human beings were so small, and particularly human females! And, when she got past the shock of the new, she noticed that her sexual feelings were different as well. They weren't as intense as they were in heat, but they weren't as completely absent as they were when she wasn't in heat as well. She remembered two humans turned mares arguing about whether being a human female meant being "always in heat" or "never in heat" and she could see why neither phrase was entirely descriptive.
Anyway, time to put stage two of her plan into motion.