First, every day was exactly like every other day - same schedule, practices, food, and sleep day for 100 days.
During every part of the retreat, day and night, I repeated the Great Dharani, a 450-syllable mantra that takes away the holding and checking mind. Sometimes I said it out loud, other times I repeated it silently.
I took all my food into the retreat at the beginning. Breakfast was steel cut oats with dried fruit and nuts. Lunch and dinner were brown rice and lentils. Unfortunately I couldn't digest the lentils and after 60 days of acid reflux and diarrhea, I made a call for peanut butter. I also had carrots and apples. These simple meals took about 20 minutes to prepare, eat and clean.
The daily schedule was:
12 midnight - 1 a.m. 108 bows, sitting meditation
4:30 a.m. - 7:30 a.m. 108 bows, chanting, sitting meditation
7:30 a.m. Breakfast, work period, break
10 a.m. - 12 noon 108 bows, sitting meditation
12 noon Lunch, break
1:30 p.m. - 3:30 p.m. 108 bows, sitting meditation
3:30 p.m. - 4:15 p.m. Walk outside
4:15 p.m. - 5 p.m. Sitting meditation
5 p.m. Dinner, break
6:30 p.m. - 9:30 p.m. Chanting, 108 bows, sitting meditation, chanting
In the weeks leading up to the retreat, I found it impossible to imagine sitting for 100 days - the time span was just too vast. But once the retreat was underway, all I needed to do was follow the daily schedule and then my idea about 100 days evaporated.
Long solo retreats are commonly undertaken by seasoned practitioners in the Korean Zen tradition (as far as I know, Japanese and Chinese Zen traditions don't generally include retreats of this type), but anyone can create a shorter solo retreat. It's a remarkable way to investigate this precious human life.