When the Dalai Lama was asked about meditation he replied that he meditates for two hours a day, unless he is busy. If he has a busy day coming up, he meditates for three hours.
Even on the busiest days, make sure to have 30 min “me time”. Add the “me time” to your “to do” list.
Me time purpose should be fun and/or relaxation. This habit will allow you to keep your batteries running and be more efficient.