I can't quite believe I did it, but I did! After spending 3 hours in the car coming back from visiting family I was ready for some fresh air and time on my own. I set off thinking that the only person putting pressure on me to do it was me, and that took off most of the pressure straight away. The whole thing was tough, and S L O W, but I did it.
I was trying to think about the week ahead to take my mind off my thighs telling me that they hurt, but in the end my thoughts took the usual pattern of "one leg in front of the other, one leg in front of the other".
Am now treating myself to coffee and toast and The Killing III. Thankfully won't be running again until Wednesday evening...
Thanks for all the words of advice and support that I've received. Just knowing that other people have been there too helps so much!