HOW IS THIS FOR A MEDITATION CHALLENGE. . . .

Zen master Guo Jun was a resident of Singapore when he became seriously interested in Buddhism.  At age 14 he went on his first seven day retreat.  A few years later he was ordained as a Buddhist monk and engaged in a variety of meditation styles and retreats.  Upon learning that the Korean Zen tradition offered one of the most rigorous 3 month retreat programs, Guo signed up for two of them:  three months in the winter and then three months in the summer.  In his book, Essential Chan Buddhism, Guo outlines the daily schedule for the three months:  (he says it was "brutal")

• We woke at 3:00 am and finished at 11:00 pm
• We had only fifteen minutes each for breakfast, lunch and dinner
• Toilet breaks were five minutes, but the toilet was far from the meditation hall so we just went outside
• For ninety days we did not take a shower but had a basin of water that was filled from a bamboo pipe that ran down the mountain. We used a towel to scrub ourselves clean.
• There were no break times
• Most meditators weren't even assigned a room but given a folded up cushion to sit on which could be opened for a bed.
• They slept in the meditation room
• Each sitting was at least an hour and we had to sit in full lotus
• No movement was tolerated.  If monitors, who were senior monks, saw us move an inch, they'd hit us with the incense stick
• After every morning walk we had to do 108 prostrations in only ten minutes.  Up and down, up and down,. It looked like we were doing jumping jacks.
• Then there is pain, so much pain. Tears foll down from your eyes as you come out of full lotus. There is so much pain that you don't know where the pain is coming from.
• The food was kimchi all the time, kimchi and white rice.  The kimchi smelled like rotten eggs. It was repulsive, almost unbearable. It made me gag.
• In the middle of the retreat the practice was intensified for seven days: we were ot allowed to lie down. Twenty four hours of continuous sitting practice for seven straight days.  We learned how to sleep while sitting, but when you were caught dozing, you were hit. You learned to sleep without moving.
  

As the retreat went on, Guo realized why it was nicknamed "demon training camp."

Here's the point:  you may not want to do that kind of meditation retreat but . . . . surely you could sit once a day for 20 minutes!