I felt the same way last year. I could easily walk 10 miles and could knock the heck out of the elliptical, but running was impossible. I had never in my life been able to run a mile without stopping.
But I decided to make running 3 miles without stopping a goal. I would run a minute then walk a minute. Then I got to running two minutes and walking two minutes. Eventually, I ran five minutes then walked two minutes. I kept working my way up so I was running more than walking. Before I knew it, I ran a mile without stopping. Then two. Then three! Eventually I got up to five miles without stopping.
I did this on a treadmill. I decided to try running outside and it felt surprisingly different. Harder. But it enabled me to try different inclines so it is now easy when I'm on a treadmill with a slight incline because I have done some uphill running.
I got to 6 miles, at 5.0 miles/hour. Now my goal is speed. I want to get to 6 miles in under an hour. I started on this goal last week. I had been doing 5.0 to 5.1 mph on the treadmill with a light incline (to mimic "real" running) but bumped it up to 5.5 mph. I walked 2-3 minute and ran 2-3 minutes. Then I went to 5.6, 5.7, ...all the way up to 6.1 mph, walking 2-3 min and running 2-3 min. Then I started at 5.5 again. That made 5.5 seem so easy and doable!
I feel so proud to be able to run, so I hope you find a way to do it. Start slowly, even if it is just one minute, and work your way up. Couch to 5k, as others have mentioned, is also a good method of working your way up.
Good luck!
