Unless your physician is of the opinion that your particular issues would benefit from more rest, you first have to believe that exercise will (eventually) make your life better. And it's not a wild stretch, because all evidence points in that direction.

If you don't really believe that, man, it's super fucking hard and the first step has to be a psychological shift. I would wholeheartedly recommend a professional, if that is in the books for you.

If you do however believe that exercise will eventually improve your life, then make it harder to say no: Join a club, any club, that involves moving your body. Hire somebody, depending on where you live maybe insurance coverage will get you going for cheap/free.

The gains in the beginning are hard but boy do they come quick.