Why a wave and not a wall
Most people meet a craving as something to be resisted: braced against, argued with, white-knuckled through. That framing has a problem built into it: resisting is effortful, effort runs out, and the moment it runs out feels like proof that you were always going to lose.
A wave is a better description of what is actually happening. It arrives, it steepens, it breaks, it recedes. You do not have to defeat it. You have to still be standing when it has gone past, and it will go past.
How people do it
Notice it and name it. "This is a craving." Saying so, even silently, puts a small amount of distance between you and it: you are the one observing the thing rather than only the thing.
Find it in your body. Tight chest, restless hands, heat in the face, a pull in the stomach. Cravings are physical, and locating one gives your attention somewhere concrete to be instead of on the story about what you could do to make it stop.
Keep breathing, steadily and unremarkably. Nothing elaborate. Slow out-breaths, because that is the half most people shorten without noticing.
Let it rise without arguing. The urge is allowed to get stronger. It is supposed to. The aim is not to hold it down; it is to still be there when it stops.
Watch the time go by. This is where a clock earns its place, and where the direction matters more than people expect.
Count up, never down
A countdown is a contract with a failure state. Set ten minutes and stop at seven, and the timer has just told you that you fell short of something, at the exact moment you least need to be told that.
A count-up timer cannot do that. There is no minimum, nothing to fall short of, and every second on it already happened. Two minutes is two minutes you rode out. If you stop, you stop having done something rather than having failed to do something.
Rate it before and after
Give it a number out of ten when it starts, and another when you come out the other side. This takes five seconds and it is the single most convincing thing you can do, because in a month's time the argument "it passes" will be made in your own handwriting rather than by an article.
Over time the pattern in those numbers is more useful than any individual one: what you tend to reach for, what state you were in when it turned up, and roughly how long yours take.
If it does not ease
Sometimes you sit with one and it simply stays hard. That is the same work as the times it drops. You did the difficult thing; you just did not get paid for it on that occasion. It counts.
And if a moment feels bigger than riding it out: in the US the SAMHSA national helpline (1-800-662-4357) is free and confidential, and the 988 Suicide and Crisis Lifeline is there in a crisis.