I’ve had many start-up failures alongside a few wins. The wins kept me going. It's cliché to say, but failure is a great teacher. And humbler.
My biggest lesson is that launching something without experimentation and de-risking is the most painful and time consuming thing you can put yourself through as a founding team.
I take a human centric approach which helps me in understanding customer needs, understanding retention, churn, engagement and ultimately a great product.