Granny23 .... I read your post and felt a surge of empathy, and shared pain.
Some few years ago I was persuaded, by a supposed friend, that my various needs for an exercise class, a flatter tummy, and a time-out which was just plain fun, could all be met under one roof ...if I just joined her village belly dancing class.
Now perhaps I should have realised that the locale and demographics would mean the hall would be full of 'yummy mummies' with already flat tummies and hips which did things mine hadn't done for years.....all of them simply gleaming with judgemental glee at sight of a newcomer.
And I should also have realised that if one has never had any co-ordination, one is not going to suddenly discover it in a village hall, with tinny music and a set of strap-on bells that jingle out of sync whenever you move. Ditto with any sense of rhythm, which was never my forte and abandoned me altogether when asked to move my hips one way and my knees another!
I have never in my life felt more embarrassed for myself, or more like a giraffe on speed!
I would like to have said "never in my life, before or since" ..... however the shame of failing utterly as a dancer was trumped by attempting yoga and being asked by the teacher to sit at the front of the class because I was a danger to myself.
Some people are simply not physically suited to exercise 
4 weeks to go and we both have still 4lbs to lose to get down to target weights, which I'm sure we will manage. Speech still not written but other than that I think we are good to go.
yet.