Time

Time is a non-recoverable asset.  You can't save it up and use it later.  You have to make the most of every minute as it is happening.  Despite any plan you may have, time marches on.  While those minutes tick away, there is something you can do.  You can manage your processes and improve your efficiency.  If you find yourself playing catch-up constantly, you know you have room for improvement.

Learn to balance your time invested with the expected tangible results in mind and you will make better use of the limited time you have.  How do some people manage to get hundreds of things done while you can only manage a dozen?  More than likely, it is a matter of prioritization.  Take a look at yours and see where you stand.  I find that the busier I am, the more efficient I become.  Your results may vary.