Well, a late happy birthday for what it's worth!
Birthdays do bring up reflections on where our life is going, so you are probably going through one of those "reassessment" stages where you note the passing years, ask yourself what you've done and what you still want to do.
I know the feeling of being home and having too much time and too little money. I also know now having too LITTLE time. Too much time sounds delightful, but when I have that, I know that I, too, go crazy! I think I just always need projects to be working on, or I go stir-crazy, and with all the complications life has thrown up, I've really appreciated having a brain that's been too busy to think about anything too hard!
Definitely not too old to do something new, Cate! You're only as old as you feel, and whilst it gets hard for OTHER people to accept, people can and do do amazing things in older years. I've never actually "retrained", though I had all sorts of dreams of doing so - rather I've just fallen into doing what I do, but it does give me a focus and direction for my energies and any meagre talents I might have. I have lots of fun trying out new ideas!
I won't hog your thread too much today - will go over to my diary and update some news, but hope things look up for you today. You've already made one HUGE achievement and life change in the last couple of years - one that means you are healthier and happier today, and more ready than ever to enjoy the years that are coming. If you have a happy husband and healthy and happy kids, give yourself a big tick that you've done lots of things right.