I'm in the exact same boat as you claretdebs. However, what i have found is the following.
For a week or so, just do 30 min-1 hour walks, varying your pace. Walk over rough terrain if possible such as woodland or fields.
After a week or so, start the couch to 5k program, but modify it. Instead of the 1 min jogs, then 90 sec walks, do 30 sec jog, 2 min walks. Do this until your endurance improves enough for you to start on the plan properly. It might take a week or two, it might take a month. All the while though, your endurance is improving and increasing.
While you are doing this, change your diet so you start losing weight purely through that. From then on, things should slowly start falling in place.
I've been trying to do the Couch to 5k running course, but i'm having trouble with it. I'm on week one at the mo, and i get half way through the 30 mins and i feel like i'm going to collapse. This has pretty much demotivated me from continuing, since if i cant manage to do a 30 min run/walk, how am i ever going to do more?
Some background on me. I'm 31, 5ft 10, 238 lbs, and i've recently started on a diet. (lost 4lbs in just over a week).
I have decent upper body strength as years ago, i used to play rugby, and also had a full time manual labour job, which kept my upper body pretty fit.
Should i stick to the Couch to 5k plan, or should i lower it to 15 mins instead of 30 for a week or two and do some biking on my off days? I'm also thinking about signing up with my local council run gym to help lose weight and improve my fitness.
I'm getting to the point where i'm about to give up on it all, as i really want to start running and get fit, but my body just seems to be saying no.