Jennifer Aniston had to face her biggest fear while filming <em>Cake</em>

Los Angeles - Jennifer Aniston almost drowned when she was a child.

The Cake star, who is engaged to the Leftovers star Justin Theroux, has revealed she developed a deep fear of being underwater after she crashed her tricycle into a swimming pool when she was younger.

She said: "I basically have a real fear of going underwater. I was a kid and I was riding this tricycle around a swimming pool and I drove my tricycle into the swimming pool and I didn't let go and my brother tried to help me. So, I can't go underwater and no one will believe me. I honestly can't."

The 45-year-old actress' phobia made filming some scenes in her new movie, in which she plays a woman who suffers from chronic pain and a prescription painkiller addiction after surviving an accident, extremely difficult because her character undergoes water therapy and she was forced to shoot one scene in a swimming pool 30 times, according to E! News.

The former Friends star is tipped to be nominated for an Oscar for her performance in the gritty film, which was something she had been "dying to do for years".

She said: "It's like a catch-22. It's you know, 'Please let me play this part. I know I can do it.' But then they won't give you the part because they don't know if you could do it.

"So, it's hard. You have to just wait for that wonderful brave human being who sort of says, 'This is interesting to me and all of us to take the risk and be bold.'"