No one has to be a Buddhist in order to chuckle ruefully at the observation that I once heard in a Zen context:
"Understanding is knowing to look both ways when you cross the street. Practice is for the bus you didn't see coming."
No one needs convincing. Robert Burns was among hundreds of others who pointed a partial finger at a similar situation: "The best laid plans of mice and men/ Do oft times go awry," he wrote approximately.
So, Buddhist or not, the observation and the principle are the same. Planning is common-sensical and sometimes successful; fucking up or coming to grief is inevitable.
Robert Burns pointed at the human reality, a reality that anyone might strive in vain to ameliorate: When things turn out well, there is pleasure; but the batting average for things' turning out badly is still pretty high. Some resign themselves: If it's a 50/50 split between pleasure and displeasure, well, maybe that's the best anyone could expect. Still the longing may remain ... how to sidestep or elude or come to terms with the downside, the times when things go awry.
Formulas for finding such escape routes abound: Money, sex, possessions, employment, intellect, religion, family ... the list goes on and on and yet the principle remains unmoved ... win some, lose some, but the bus you didn't see coming can be pretty painful.
"Practice is for the bus you didn't see coming."
Here in the United States, "the pursuit of happiness" is enshrined in our Constitution. The Constitution does not assert that everyone has the right to be happy, only that they have the right to pursue happiness. And pursue we do.... money, sex, possessions, employment, intellect, religion, family, etc. Most have tried a hundred different practices in their pursuit. Some work, some don't and if the batting average is 50/50, maybe that's the best anyone can expect.
In Zen practice, the practice that may begin as another way to elude the bus we didn't see coming and to pursue happiness, things are a bit different from other practices. Zen practice suggests that investigating the planner of common-sensical plans is itself the most common-sensical course. Who exactly is making all these plans whose batting average never seems to get much above .500? Since one of the bedrock building blocks of Zen practice is zazen or seated meditation, the whole thing can seem pretty ridiculous: How can sitting down, straightening the spine, sitting still, shutting up and focusing the mind have anything useful to say about my "best laid plans?"
I leave it to others to wax lyrical about the wonders and practicalities of Zen. My salesmanship has largely run out of steam. All I can say is that if all the other wondrous answers have, in one way or another, fallen on their faces, then zazen may be worth a shot. The practice may begin as a new and novel way to seek relief, but not even the best snake-oil salesman can tell anyone else whether this practice actually works. If someone wants to know -- if getting hit by the bus you didn't see coming becomes compelling enough -- well, then it might be worth trying. Do it or don't do it -- there is no other way of knowing.
The intellectual and emotional support and delight that may be found in the fact that men and women of the past have tried it and speak highly of Zen may nudge the effort forward. The notion that there is some mystical 'lineage' that "extends all the way back to the Buddha himself" (gag) can be inspiring. But whatever the support structures, still the fact remains ... do it or don't do it; there is no other way of knowing for sure.