I've been between 10st8 and 11st6 since 1974, so I'm not offering any advice on how to lose large amounts of weight
However, the one thing that the diet-fanatics dont like to advertise is that if you semi-starve for over 48hrs your body goes into a sort of famine mode and starts breaking down unused muscle to use as food, and lays fat down so you can survive the famine/winter that it has evolved to cope with.
The answer is to moderate your food intake while you increase your regular activity level enough to increase your average metabolic rate.
Then keep up the activity level and be patient.
The weight usually took a long time to put on, so you shouldnt expect it to take 10 minutes to lose
[/end advice from another stick insect]
ps
oh ! and what activities do i recommend ? well I like to run on the south downs for a couple of hours at a time, or mountain bike on them for 3-4 hours, and I used to windsurf in up to force 8 gusting 10 in 6m waves, and boogie boarding, and motorcycle trials, and mogul skiing.
in other words just go out and do stuff !
it really doesnt matter so long as you get carried away cos you're enjoying it.