"No battle plan survives contact with the enemy"

(As popularly reduced from a saying of Helmuth von Moltke the Elder).

Well the weather did not quite cooperate, and neither did the CFS, but the day was not failure or disaster.

Demonstrated: that fifteen minutes of steady-paced gardening, in three five-minute sessions over three hours can achieve a significant difference to my garden.
Also demonstrated: While not pushing hard at the limits of my stamina, doing that every day would not be wise, even given good weather.  Let's aim for every other day.
Even with my visiting gardener's assistance this remains a "sinking slowly" situation, but that is better than the garden and the railway sinking quickly into wilderness.
Come the winter, if the weeds stop growing and I don't stop brief forays to pull weeds, the campaign will turn in my favour.  A long game, but at least I'm not, yet, having to resort to a literal "scorched earth" policy.

I've also had a little success examining the borders of inactivity.
Sometimes total passivity is required, even beyond merely paying attention to the radio (speech or music).
 But sometimes very quiet, very low impact distraction activities serve well.  A new marble solitaire puzzle seems to hit the spot, as long as concentration and calculation is not ramped up to chess-playing levels.
Similarly, restoring broken toy train locomotives, provided things are taken slowly and go well.
At the first sign of fatigue or frustration, walk away.
Or, more precisely, roll over and fall asleep, both these activities being pursued principally in the horizontal position.

So, in addition to the dead weeds, three rusty locomotive chassis, each over over thirty years old, have been restored to life.
In a manner reminiscent of Dr Frankenstein, perhaps, but such is my wont.
And precision, and perfection, eat energy.

Some earlier engines "risen from the grave", with much swapping and hacking of body parts:

Their own mothers' wouldn't recognise them.

So little done, but some little done.