Ask HN: What did Product/Market fit feel, and not feel like for you?

I just listened to the Segment founder's discussion on how they knew they'd found product/market fit. Basically, it was an explosion of demand. However, I'd argue that many companies have product/market fit without having customers beating down their doors. ie a $30k mrr bootstrapped business growing at 100% YoY. I like the idea of a data set to train your instinct on this, so was curious to hear from others: What did it feel like (or not feel like) for you?