Hmmm,

You start with 'On a Sunday without anything in the diary (and I do like to keep a full diary) what does one do..' and end with 'I enjoy days like these…'. 

So perhaps you don't always need a full diary and can sometimes just take things as they come. I say this as someone who also likes to have things planned but actually finds he enjoys the unplanned.

Apart from the Lotus bit of course; one would always plan to drive in an MX-5, but if all you've got is a Lotus, well, then you'll just have to grin and bear it.