In 1997 my doctor told me the same thing. I went out and bought a bike. I started biking to work and being a bit careful about my weight and just generally what I put in my mouth. When I went back to the doctor a month or two later, he told me that if everybody did what I did, he would write 1/2 the prescriptions that he’s writing and he would probably be out of business.
Do yourself a favor, listen to him. Once you get used to eating like a mentch and excersizing a bit, it’s not so bad and you’ll feel really good about yourself. (That in itself can help stave off the diabetes.)