I spend a fair amount of time just thinking about whether something is feasible or not, and if it is feasible, whether it's really worth doing.

I've seen Leonardo Da Vinci notebooks which are filled with tiny, messy scrawls written in mirror image across the page. I'd love to know how he kept all his projects going at once.

Every day, I walk with my dog - summer, winter (it gets -20 F in Saint Paul), rain or shine. The nicer the day, of course, the longer the walk.

In my office, I like it quiet, so I can concentrate.

I think it's important to associate with positive, upbeat people.

There are a lot of ideas I've had that I originally was quite taken with, but over time, I lost steam. They stay on my list, but between me and you, I'm probably never going to do them.

I specialize in science and history, with a special emphasis on including do-it-yourself projects in the mix. My dozen or so books have sold hundreds of thousands of copies. I'm also a contributing editor at Popular Science and at Make Magazine.