I went on a 100 mile bike ride a few days ago, the elapsed time of which was about eight hours.
For the duration I thought about NOTHING.
Only the pains in my legs and my heart and my lungs crept through on a subconscious level, but for the most part it was like being in an advanced state of meditation, almost like enjoying a particularly deep and satisfying sleep. And when I woke up, or eventually stopped pedalling, as was the case, I felt fresh, sharp and sanguine.
Some three hours after I'd completed my ride and had a wholesome feed and a couple of beers and enjoyed something clever and quirky on HBO, I went to sleep for another eight hours - fitter and hopefully healthier than I was 24 hours ago.
That's almost an entire day's worth of concentrated zen.
Get on the bike.
It works.