Who else struggled at first to get their head around them?

I was talking to some users earlier in the week and they were asking me if they should always use Whyboxes between Whatboxes.

My answer was Yes, well, mostly.

Whyboxes are a great way to get people to think about their processes, challenge the need for steps, and to agree clear handovers between people.

Useful questions to ask when you're struggling to define a Whybox;
1. What would you miss if you didn't carry out the activity?
2. What could you measure as an output of the activity?
3. What's the value the activity delivers to the next step in the process?

We used the example of defining a Whybox for 'Boil water'. How do you know it's boiled? What do you observe? Is there a measure that doesn't involve dipping your finger into the water?!

What are your best tips for defining great Whyboxes?