I'm 34, and still a long way from ER, but I left the corporate world 4 years ago to work at a family-owned internet business. I took about a 30% pay/benefits cut in the process, but it has been totally worth it. My commute went from a minimum of 25 minutes to a max of 10. I don't have to travel and be away from my family. My bosses care more about work getting done than appearance of busyness, and the dress code is very casual. I was bored stiff at my corporate job, being occupied only about 25% of the time. Now, I have more stuff to do than I have time to do it, and it's all actually productive. And there's a lot of variety in the work that I do.
And there's a lot of mustachianism going on here. Last week, there was a day when everyone in the office (ok, so it was only about 6 that day) rode their bikes to work. The newest car in the lot is a 2013 Prius, and aside from the office manager who lives 2 miles away and drives a mini van, everyone drives a fuel efficient sedan when they're not biking. Most people bring their own lunch from home, and those who don't bring their lunch walk over to the nearby grocery store for ingredients, and prepare their lunch at the office.
I don't mind still having a boss--it keeps me a bit more accountable--but I *do* really appreciate the lack of monumental corporate bureaucracy. We can have an idea for a change in the web site, and have it designed, implemented, tested, and pushed live in a matter of a few minutes to a few hours, depending on the scope.