My FI and I just completed our first half marathon on Sunday! We walked it, our goal time was 3:45 and we finished in 3:27! We started training at the end of August and have each lost about 20 pounds. It really helped to motivate us to keep up with our workouts. Our wedding is in May and we are already looking for another one to do in March or April to keep us going!
I would highly recommend a challenge like this for anyone. It was really great to do it together too!