How do I get her to pee quickly

My dog is on strict no exercise order due to a condition she’s being treated for. The vet says strict, short, leashed bathroom breaks. She only wants to pee and poop on long walks (not on our street). Advice how to get her to go in the backyard or out front of the house? She held her pee for like 18 hours in the backyard lol I was trialing the “if she has to go she will”