I met with Daniele Marino, Head of Product Development at Soldo to talk through lessons he learnt while building Soldo. 
Soldo helps businesses to control their spending, with pre-paid debit cards, virtual payment cards, and a handy dashboard overview. Founded in 2015, Soldo has raised a total of $22.2M in funding.
http://steadfastcollective.com

Jeff Gardner of Intercom shares his lessons learnt.

Dear Unexpected Entrepreneurs is the new flagship podcast for Summit, a community for entrepreneurs looking to refine their idea or grow their businesses to the next level.

An unexpected entrepreneur is an expert in their field, who has ambitious goals to innovate in their sector and push boundaries, which then, in turn, become their means for living and their own unique business.

Their goal wasn’t always to build a business, but to fill a need in a sector they're passionate about.