Most people aren't going to live past 90, so 40-45 really is middle age, but people are so weird about this, as you've said. I just turned 59 and have been living my best life the past 10 years. I definitely don't feel or act old, but there will come a time when that will be inevitable. Bring it on - it's better than the alternative. It's patriarchal bullshit that women must somehow magically stay 25 their entire lives. F that noise!