Your children are grown and your career has slowed down - all the stuff that took up so much attention is gone, and you're left with expansive time and space. You have to reimagine who you are and what life is about.
Photography was a blessing because it filled my time. If I had to start over, I'd pursue photography - probably to the exclusion of acting.
Sometimes parts just come along when it's the perfect time for you to do them.