"I lost my father when I was a kid and I didn't know about grieving," Watts said recently.
Watts said to prepare for her role in "21 Grams" she read everything she could on the subject and even attended bereavement groups.
"It just happened and (my father) was gone and a lot of those meetings that I sat in on made me realize: 'Wow! Those feelings I was having were because of that.' I didn't know how to identify them. I just knew my father was gone."
Swim Week Miami Beach 2014 [PHOTOS]