This time last year I had a not particularly respectable 5km time of around 35 minutes. Then I joined the same gym as my DH. It's a no frills affair run by an ex-para. Since then I've had to have my wedding dress taken in 3 dress sizes, run 10km, 10 mile, assault course races, half marathons and a marathon. I've also finally managed to go sub-30 minutes (in my first Parkrun) for a 5km.
All achieved by...just getting on with it. It's a not a posey gym. If you're on the weights and doing it wrong someone, anyone, will come along and help you out. I'm sure the no frills aspect wouldn't be to everyone's cup of tea but my main point is, to lose weight and keep fit you have to find something you enjoy and stick with it. I just never would have guessed my thing would have been Hatton Academy Boxing (a cardio work out - not combat - don't like punching people).