14 Day Free Gym Pass at Nuffield Health with O2 PriorityGet freebie
I did this freebie last time. Nuffield Health which are nice gyms got 14 free day gym passes. Classes come with this which to be honest is what I did most.
You have to take ID with you and sign up when you get there, but it's a super easy freebie to get going post-Summer.
Note from Tom: Expires at the end of September 2016.