Older than you
I started up again after over ten years off by rinding my 20+ yr old DeRosa, I ended up needing a new bike that fit my older body so I got a new bike also. Make sure that you ride several different bikes and sizes before buying any. Make sure that you work with a LBS that can fit you properly and who is willing to change parts if you need say a different front stem. Make sure to take a long ride, at least 1 hour on your choice be making it your final choice. You will have fun and by the end of the summer you will be in really good shape.