Looks a decent offer, Anytime Fitness: 10 Gym or Class Day Passes for £10. As a price comparison a single pass is £7.20 on payasyougogym. Plus get a £5 M&S e gift card by entering code MARKS at checkout (new account) and the gift card will be fulfilled by 21st December, more info here.
Code works on £10+ spend, so could use it on other items e.g. toilet roll, kitchen towel etc.
£10 for a 10-day gym and class pass (up to 93% off)
Valid inside and outside of London
Check the club you want to use is included in this offer by looking at the map on Groupon, 70 locations included
All passes must be used by 31 Jan 2019