Tuesday (week two): I can already do one minute longer on the stepper and my craving for lager has subsided to one bottle every 30 minutes. However, I don't feel any better - I'm working out next to a grandmother with a body like Caprice who is going four times faster than I am while carrying on a conversation with her husband.
Wednesday (week three): I can feel slight improvements, and am beginning to be recognised as a regular. I can also take more interest in my surroundings now that my glasses don't steam up so much from my body heat. I overhear snippets of conversation: "She shouldn't wear a crop top with a figure like that, look at the rolls." "Are you doing the marathon this year? It'll be the fourth since my 60th."
It is just at this moment that I miscalculate the speed of the treadmill and it throws me off. The assistant obviously thinks I have had a coronary and looks disappointed when I stand up. I still ache three days later.
Thursday (week five): GCSE results day. I am delighted with our results but disappointed that no one has noticed my new shape - although they have all spotted that the senior teacher has shaved off his moustache. I am met by sixth-form candidates who are now desperate to do an A-level. One promises me that his attitude will change; he's a very bright boy who underachieved. I accept him but mentally put him down as the 6-4 favourite to have left by the end of September.
Friday (week eight): In the gym again - what a fabulous way to start the weekend. I take out all my angst and anger on the rowing machine while watching "Neighbours" with subtitles. I feel lighter, trimmer, reinvigorated and less stressed. Plus tonight there is live rugby on big screen television.
If I was paid by these results I would certainly hit the target. Oh, and the 6-4 favourite I thought would pack it in is working very hard indeed, so there is the possibility of redemption for us all.
Tony Scully is head of creative arts at Holy Family Catholic School, Keighley