Well, Mendip's diet and lifestyle have been pretty much 'public domain' for the last few months, so here's my prescription, since he asked...
Step 1
Cut down your drinking. Especially that 'nothing' drinking when you swig back about a thousand calories just for something to do about 5 nights per week.
Step 2
Whichever form of aerobic exercise you favour.
Cost
Zero baht.
OR
......spend thousands and fanny about with it, washing down dustbin lid-sized pizzas with booze but balancing it out with whey protein drinks.