Between running a multi-billion dollar empire, attempting to head to space and updating his blog multiple times per day, Virgin Group founder, Richard Branson, gets a lot done.

His top productivity trick is a simple habit that has nothing to do with making to-do lists, checking email or turning off notifications: "The only reason I'm able to do all the things I do and to keep on top of a busy schedule without getting too stressed is because I stay fit," the billionaire entrepreneur writes on his blog.

Making time for exercise, he says, doubles his productivity.

"If people are feeling their best, they will be their most productive selves at work," writes Branson. Plus, there are other benefits: "I find exercise the most natural and effective mood booster there is."