An excellent way to lose weight, tone the body, calm the mind, and put some flexibilty back into the too long seated taxi driver is Ashtanga Yoga.
Without having to get too much into the yoga buzz, there is a guy called Godfrey Devereux who runs a yoga retreat in Ibiza, and he has a video/DVD "Dynamic Yoga". It has a 1 hour practice divided into 2 parts, energising, and relaxation/stretching. If you can even divided the 2 parts to morning and evening, or even 1 part on alternate days it will do the job. If you follow the instructions to the letter particularly "sucking the muscles into the bone", and don't eat for c. 2 hours before and after the practice, the weight will drop off quickly if you maintain the practice every day.