hubcyclist, I am in my early 30's too and I am 5'8 155 lbs so we are of similar build. I would again just suggest taking it easy but your still young enough that your body can handle some stress. Couch to 5k sounds perfect. Visit a local running store for some shoes. They are typically a little more expensive but they specially look at your feet and how you pronate and such to point you in the right directions for shoes. I pronate and need stability shoes and I have been a fan of K-Swiss shoes lately except for the fact that they seem to wear fast.

Find a group in your area to train with and you will gain a wealth of knowledge just from showing up regularly. A local guy in our area in his 20's was like 400 lbs and started working out with our local group and loves it. He's lost a lot of weight since he started and everyone enjoys him too. It's usually a very friendly community and tight knit group of people. So get started and have fun and enjoy the outside!