The Monster-in-Law star is famous for her 1980s Jane Fonda Workout videos and explains when she became involved in her many social causes she knew it would be important to be healthy and have stamina.

"I am almost 80 years old," she tells actress Brie Larson in a new interview for Net-a-Porter's The Edit. "If you want to make it to the long-haul, you have to take care of yourself. I get more than eight hours sleep every night, I meditate twice a day for half an hour, I eat right, I workout. I always tell activists, 'This is going to be a long struggle. We have to stay strong'. One reason I started my workout was because I knew that to be fully empowered, I needed to feel strong in my body."

"A woman once wrote to me and said, 'I was brushing my teeth one morning and I found a muscle in my arm that wasn't there before. I went to work that day and for the first time I stood up to my boss'," she says. "It's easier to be brave when you feel strong."

Fonda has previously opened up about using regular exercise to help her maintain her health as she grows older.

"I stay active, I hike, I walk, do resistance bands, Pilates and yoga - you've gotta move," she told last year (16). "The saying 'move it or lose it' is so incredibly true but more so especially when you're older. If you don't keep moving you go downhill really fast when you're older.

"Young bodies are more forgiving, so if you're not regular about working out, it doesn't show up right away but it does when you're older."