Hi Lizzy,
Well done on losing your 6 stone, I am sure you must be very proud of yourself!
I think the gym is a good way to get plenty of health benefits whilst helping you continue to lose weight at the same time.
Have you had an induction at the gym and told the instructors what you want? They should be able to design you a program that's right for you.
Sensible is a good word to use, if I were in your shoes, I would aim for 3 gym visits a week if you are reasonably active the rest of the time, maybe for an hour each time. In terms of intensity, I would aim for a warm up of 4, and building your cardio up to 6-8 on a scale of 1-10, with 1 being laying in bed and 10 being 100% effort as hard as you can. Obviously if you have any medical issues, you should contact your GP first and inform the gym staff.
Does that help in any way, is it what you were looking for?
Thanks,
Neil.