Aniston, 45, revealed about the same on the red carpet at the 2015 Screen Actors Guild Awards, where she was nominated for best actress in 'Cake'.
"(I didn't exercise) for a couple months and it helped with your mood, the physical and all of that," she said.
Aniston realised later that exercise is very important for body.
"At first I was thrilled, because I said this will be so great I don't have to work out. After a few weeks it really does start to affect your sleep, your stamina throughout the day, your mood... We take for granted how important (exercise] is and why we do it," she added.