Gil offered this simple concentration technique for our walking meditation:
Use counting as you walk slowly back and forth. Give one count to each step, to actively encourage being present for that one step. Keep track of count as you go, counting up to 5, then start over, this time counting until 6. Then over, until 7. Then over, until 8. Then over, until 9. Then over, until 10. Then back down to 9, then down to 8, then down to 7, . . . then down to 5. Start over from beginning, starting with count up to 5, . . . Throughout, making sure that count is soft and relaxed, but also committed. If you lose count, don't worry, just start again from the beginning. And observe how it carries over into subsequent sitting meditation.
I took Gil's instructions to heart. I was going to make it through the 45', without skipping a count. Counting, counting . . . easy at first, surprising myself by how good I am with this. After a while, boredom, and a glance at the clock. 30 more minutes to go. I concentrate even harder, not enjoying process really. Feeling strain in the brain. Looking at the clock more and more often. Meanwhile keeping up still. I am going to make it to the end. Never mind nascent headache. I notice some people taking a break, and having some tea. Not me! Counting, counting, competitive streak is taking charge. By the end of the session, I inherit dim satisfaction from drill well done, and discomfort from full blown headache.
I tell Gil about the strain from concentrating so hard, and the headache. His answer: "You were trying too hard. It is supposed to have the opposite effect. You should be feeling relaxed afterwards, not more tense." Interesting how I took on the 'committed' part of Gil's instructions, and used it to feed my natural tendency towards competitiveness.