She told Interview magazine: "I've been doing a lot of hard thinking. I know that sounds weird, but I'm at a time in my life where I'm trying to figure out who I am at this age. A happy grandmother.
"I've done some things this year that really were a gift, and I worked with people I really wanted to work with. Michelle Williams, Jennifer Lawrence ...
"I don't know what I'm going to be doing next work-wise. My gardener quit in the height of the heat dome this summer, so I had to rescue my garden. That was a very grounding thing.
"I'm doing a self-search now. I just went to a week-long meditation retreat."
Sissy went on to insist she's just enjoying spending more time with her husband, production designer/director Jack Fisk, as they get older.
She added: "We're all home right now, so it's a real precious time. And we're getting older, my husband and I. We're elderly for god's sake."
It comes after Sissy previously admitted luck has played a big part in her success, which has included winning an Academy Award and three Golden Globes.
She told The Independent newspaper: "I know really great artists. And so much of my success has been because I've been at the right place at the right time."
Sissy has starred in a host of successful movies during her career, including Terrence Malick's crime film Badland and the Oliver Stone-directed JFK.
But she believes there are many other actresses who are more talented than she is.
Sissy added: "I met Terry Malick, and then went from that to ... you know, I kind of represented the young everywoman of the 70s, and then one thing led to another. There are people who are far more talented than me ... so many great artists out there who don't ever get the break."