Why billionaire VC Marc Andreessen schedules every second of his day, including 'critical' free time

Billionaire and legendary investor has every second of his day and night scheduled, including free time and time to think — and the practice is critical to his success, he says. 

"The big thing is basically *everything* is on the calendar. Sleep is on the calendar, going to bed is in there and so is free time," Andreessen, 48, a co- of Silicon Valley firm Andreessen Horowitz, told angel investor and Twitter, and Snap alum Sriram Krishnan for a story published on The Observer Effect website on Saturday.

"Free time is critical because that's the release valve. You can work full tilt for a long time as long as you know you have actual time for yourself coming up. I find if you don't schedule enough free time, you get resentful of your own calendar," Andreessen said.

While today keeping such a meticulously booked and color coded calendar gives Andreessen a sense of calm ("If I didn't have this, I'd be in a panic the very first moment I wake up," he said), it wasn't always that way.