FWIW, I've dropped 43lbs since January, and the most exertion I have is launching a golf club into the air after a bad shot. It helps to have a lot to lose, but this has been achieved by - mostly, but not religiously - avoiding fatty and/or fried foods and eating less. I avoided beer for a while too - sticking to red wine and spirits - but I have since fed beer back into my diet. Also, avoid eating when drunk.
I'm now at the point where I think I can go to the gym (actually, pool, I prefer to swim) without feeling completely out of place. I also have to go clothes-shopping this weekend, as I don't own a pair of trousers that won't fall directly to the floor as soon as I undo my belt. Luckily, Nordstrom's is having a sale (that don't make me gay, right?)