Pivoting. It was originally a grocery price comparison app. That was illegal (long story). So we pivoted to a recipe app and try to sell ingredients. We looked at other recipe apps like Cookpad and felt that what they were missing was quality control.
We wanted a quick and dirty prototype that was a subset of the grocery market, so that if it didn't go well, it would just be controlled damage.
I was following a low carb diet so I did a low carb diet app, solving my own problem. There were some blogs and a crappy app that did this. The Facebook group had too much traffic to keep track of recipes and no quality control, so half the recipes were terrible. We released the app, expecting about 30 downloads but it was 1200 and crashed the server temporarily. We also got some feedback that calorie count wasn't helpful, so we switched to carb count, and were the only ones on the market to compile all the local recipes and have carb count for them.
The business model canvas helped a lot in the process. We drafted a business model, then identified the riskiest thing and tackled that. At first it was the business proposition (which went from find food > eat healthy > lose weight). Then it was revenue model (sell directly, instead of ads). Then operations, delivery. The target market was unintended and we could well have missed it, because low carb diets aren't part of the culture.