Stretch

The very idea of getting out there and doing some sort of physical exercise depresses you. It is contrary to your beloved Couch Potatoe image. Yes, you'd look like a dowling ball in one of those spandex outfits. Ok, skip the outfit. Go for comfortable clothes instead. Something loose fitting. And forget the car keys (that could be quite traumatic in itself but nothing is easy).
And go for something manageable. A walk around the block, a brief excursion to the nearest park That should suffice for that big first step.