Sosa Sensei taught me a technique he gleaned from either Tohei Sensei or Takahashi Sensei:
While in seiza, rock from side to side concentrating on the movement. Try to be like an upside down pendulum. Each rock should get smaller and smaller until the rocking is contained in your mind.
It took me a while to get it. But, once I did, I found it was much easier to return to that "special place" where the rocking was in my mind. And time flies by.