Start to eat more healthily... for me this just meant eating less chocolate
Then there are plenty of other forms of exercise besides running that you may find easier

. Walking, swimming, biking... Joining, or just using, a gym might be a good idea because they have a large range of machines you can use
I was like you, wanting to get fit but useless at sports. Except once you get into it, if you're willing to except that for the first few weeks you wont be able to do alot, then you see a great improvement in what you can do
