Yeah, potato-only sounds rough. I did a sweet potato cleanse once. Failed by lunch day two. Learned to add variety. Roasted some broccoli on the side. Made it tolerable for a few more days.
Read this study last week that basically said single-food diets are setup to fail. Our brains just crave variety after a while, lol. The researchers found that even adding one extra vegetable like broccoli can significantly improve compliance. It's not just about willpower, it's about how our taste buds get bored. I remember hearing a nutritionist say that the key to any diet is making it something you can actually stick to. So yeah, your approach with the roasted broccoli sounds spot on.