...and I owe big thanks to AliB1 for the encouraging answer to my question last night! I was out there at 6.30 this morning and it really wasn't too bad - bizarre that I found it such hard work on Wednesday.
As suggested, I took it v-e-r-y slowly and paced myself, and couldn't believe it when I could even run faster for the last 60 seconds (the heavy breathing causing some alarm to passers by...). Just hoping the tomato face calms down before heading out to a meeting.
I'm really beginning to believe I might be able to finish the plan and win my 'graduate' badge! Then the task will be to improve my speed - I suspect I'm hardly running any distance at all.
CaroleC and Grammadog1947 - your encouraging answers are much appreciated too!
Thank you to everyone in the community for the blogs and questions - it makes a huge difference reading other people's experiences.