It took me much too long to realize this, but there's a fundamental difference between a Startup and a Muse. A Startup is about creating something new, which takes years to develop, can scale hugely, but may never turn profitable.

A Muse is a form of passive income, and although it's still hard work, it can be built much quicker. The reason for that is that a Muse does not create something fundamentally new, it's usually a very conventional product in a well known market.

I read the Four Hour Work Week years ago and love the idea of creating passive income to work on other things. But my natural tendency is to build startups, not muses.

Besides, if your hourly rate is high enough and your spending low enough you can travel the world for less than a day of contractor work a week.

So if you're still interested in building startups, my next piece of advice is to really read up on Customer Development. Read Ash Maurya's Running Lean http://www.runningleanhq.com/, Eric Ries' upcoming book (he also has some lectures on Udemy) and Steve Blank's blog, in particular about the class he gave at Stanford.

Key takeaway for me: figure out what people are willing to pay for, before you actually build it. Of course there's a tradeoff where it makes sense to just quickly build it first, but I've been trying hard to move that threshold from 3 man-months to a few days.