Our family did the 1/2 and My daughter and I want to do it again. After I swore I would never do it again. But like others here if we keep in shape during the year we should have no problem.
I walked it in 3:09, my daughter and husband jogged it in 2:59 I was only 10 min behind them. I'm 53, overweight and loved every minute of it (except when I fell in mile 1).
Go for it, you have a year to train and a goal that you can reach.
denise