I'm fat, I'm fifty, I'm unfit and I can't run. When I was young and slim and fit I couldn't run either. I've never been able to run. Build, lungs, laziness, injury and cigarettes were some of the elements in play. My only grumbles during six years in my local TA Battalion were the runs. I failed most BFTs I ran first time (3 miles - 1.5 in 15 minutes as a squad, 1.5 best effort with a cut off time of 10.5 minutes) and relied on others to shout me around in the time.
So now, 28 years later, I'm going to follow couch to 5k and end with an attempt at completing a BFT in the old timings. It's a tall order and it's going to suck. I'm going to hate it. There's no question of it being fun. But it'll be good for me if I don't die trying.
If you see me and want to run along for any distance then please do!