There is a simple reason why we procrastinate: We assume we will have more time. There is more time to make it perfect, more time to connect with others and more time to pursue that brilliant idea. But success lies in knowing that time will run out - and that we will die.

In two decades, successful entrepreneur Ricardo Semler turned Semco Partners from a four million dollar company to a 212 million-dollar company - namely by creating an intuitive, innovative work environment, shared in his best-selling book Maverick. Semler is also a very happy man, but he says it has nothing to do with his financial or business success. As he recently explained to Tim Ferriss, Semler's real secret is treating each day as his last.

I kept thinking 'Geez, I don't want to be in that situation where suddenly now I have to go to ballgames with the kids and I have to travel to places I haven't been and I have to write that play that I never wrote.' That's crazy. Let's do something else... So, on Mondays and Thursdays I have what I call 'Terminal Days', the two days a week in which my schedule is completely clear and I do on those days what I would have done if I heard this conversation from my oncologist.

This habit isn't just for show. Semler says melanoma runs in his family, so most of his relatives have had a sudden death. He himself has had multiple cancer surgeries that, fortunately, caught the melanoma before it spread. Even though he is 57, Semler faces his own death every day.

Semler sets aside two days a week to do exactly what he would do if it were the last day of his life. It is easy to assume that his work would suffer, but, in fact, he is regularly setting himself up for career greatness. Think about it: If you actually carved out time for personal fulfillment every single week, imagine how focused and productive you would be during the remaining days?

For the ambitious among us, our problem isn't saying "Yes" (as Shonda Rhimes said in her TED Talk), but in saying "No". You have to close a number of doors to truly do what you desire - and material or worldly success only increases the choices over time, making the process even more difficult.

Start making tough decisions now before they get tougher over time. What should you be focusing on today?